From 6bb4b4facfe3724516f75df0ceecba9e6ff5aa8a Mon Sep 17 00:00:00 2001
From: Alexander Guril <alexander.guril02@gmail.com>
Date: Fri, 14 Aug 2020 13:36:49 +0200
Subject: [PATCH 1/3] LANG-1598 Use JSR-305 for Null-Analysis

---
 .gitignore                                     |  2 ++
 pom.xml                                        | 10 ++++++++++
 .../apache/commons/lang3/arch/Processor.java   | 18 ++++++++++--------
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/.gitignore b/.gitignore
index c30f980e360..f2822bca0de 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,3 +18,5 @@ site-content
 .project
 .externalToolBuilders
 .checkstyle
+/.apt_generated/
+/.apt_generated_tests/
diff --git a/pom.xml b/pom.xml
index e833726536e..6b98d2e7dd4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -515,6 +515,16 @@
 
   <!-- Lang should depend on very little -->
   <dependencies>
+  
+  	<!-- provided -->
+  	
+  	<!-- https://mvnrepository.com/artifact/com.google.code.findbugs/jsr305 -->
+	<dependency>
+ 	   <groupId>com.google.code.findbugs</groupId>
+  	  <artifactId>jsr305</artifactId>
+  	  <version>3.0.2</version>
+	</dependency>
+  
     <!-- testing -->
     <dependency>
       <groupId>org.junit.jupiter</groupId>
diff --git a/src/main/java/org/apache/commons/lang3/arch/Processor.java b/src/main/java/org/apache/commons/lang3/arch/Processor.java
index 563fefeb7f1..130c6da44e6 100644
--- a/src/main/java/org/apache/commons/lang3/arch/Processor.java
+++ b/src/main/java/org/apache/commons/lang3/arch/Processor.java
@@ -16,6 +16,8 @@
  */
 package org.apache.commons.lang3.arch;
 
+import javax.annotation.Nonnull;
+
 /**
  * The {@link Processor} represents a microprocessor and defines
  * some properties like architecture and type of the microprocessor.
@@ -57,9 +59,9 @@ public enum Arch {
          *
          * @since 3.10
          */
-        private final String label;
+        private final @Nonnull String label;
 
-        Arch(final String label) {
+        Arch(final @Nonnull String label) {
             this.label = label;
         }
 
@@ -68,7 +70,7 @@ public enum Arch {
          *
          * @return the label.
          */
-        public String getLabel() {
+        public @Nonnull String getLabel() {
             return label;
         }
     }
@@ -106,8 +108,8 @@ public enum Type {
         UNKNOWN
     }
 
-    private final Arch arch;
-    private final Type type;
+    private final @Nonnull Arch arch;
+    private final @Nonnull Type type;
 
     /**
      * Constructs a {@link Processor} object with the given
@@ -116,7 +118,7 @@ public enum Type {
      * @param arch The processor architecture.
      * @param type The processor type.
      */
-    public Processor(final Arch arch, final Type type) {
+    public Processor(final @Nonnull Arch arch, final @Nonnull Type type) {
         this.arch = arch;
         this.type = type;
     }
@@ -128,7 +130,7 @@ public Processor(final Arch arch, final Type type) {
      *
      * @return A {@link Arch} enum.
      */
-    public Arch getArch() {
+    public @Nonnull Arch getArch() {
         return arch;
     }
 
@@ -139,7 +141,7 @@ public Arch getArch() {
      *
      * @return A {@link Type} enum.
      */
-    public Type getType() {
+    public @Nonnull Type getType() {
         return type;
     }
 

From f48d444557724a7bcb492f7b4e01f1be44f6ed10 Mon Sep 17 00:00:00 2001
From: Alexander Guril <alexander.guril02@gmail.com>
Date: Fri, 14 Aug 2020 14:06:00 +0200
Subject: [PATCH 2/3] Update ThreadUtils

---
 .../org/apache/commons/lang3/ThreadUtils.java | 65 +++++++++++--------
 1 file changed, 39 insertions(+), 26 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/ThreadUtils.java b/src/main/java/org/apache/commons/lang3/ThreadUtils.java
index fef3dc85025..1492016fee9 100644
--- a/src/main/java/org/apache/commons/lang3/ThreadUtils.java
+++ b/src/main/java/org/apache/commons/lang3/ThreadUtils.java
@@ -21,6 +21,10 @@
 import java.util.Collections;
 import java.util.List;
 
+import javax.annotation.Nonnegative;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 /**
  * <p>
  * Helpers for {@code java.lang.Thread} and {@code java.lang.ThreadGroup}.
@@ -34,7 +38,7 @@
  * @since 3.5
  */
 public class ThreadUtils {
-
+	
     /**
      * Finds the active thread with the specified id if it belongs to the specified thread group.
      *
@@ -49,7 +53,7 @@ public class ThreadUtils {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Thread findThreadById(final long threadId, final ThreadGroup threadGroup) {
+    public static @Nullable Thread findThreadById(final long threadId, final @Nonnull ThreadGroup threadGroup) {
         Validate.notNull(threadGroup, "The thread group must not be null");
         final Thread thread = findThreadById(threadId);
         if (thread != null && threadGroup.equals(thread.getThreadGroup())) {
@@ -72,7 +76,7 @@ public static Thread findThreadById(final long threadId, final ThreadGroup threa
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Thread findThreadById(final long threadId, final String threadGroupName) {
+    public static @Nullable Thread findThreadById(final long threadId, final @Nonnull String threadGroupName) {
         Validate.notNull(threadGroupName, "The thread group name must not be null");
         final Thread thread = findThreadById(threadId);
         if (thread != null && thread.getThreadGroup() != null && thread.getThreadGroup().getName().equals(threadGroupName)) {
@@ -95,7 +99,7 @@ public static Thread findThreadById(final long threadId, final String threadGrou
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<Thread> findThreadsByName(final String threadName, final ThreadGroup threadGroup) {
+    public static @Nonnull Collection<Thread> findThreadsByName(final @Nonnull String threadName, final @Nonnull ThreadGroup threadGroup) {
         return findThreads(threadGroup, false, new NamePredicate(threadName));
     }
 
@@ -113,7 +117,8 @@ public static Collection<Thread> findThreadsByName(final String threadName, fina
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<Thread> findThreadsByName(final String threadName, final String threadGroupName) {
+    @SuppressWarnings("null")
+	public static @Nonnull Collection<Thread> findThreadsByName(final @Nonnull String threadName, final @Nonnull String threadGroupName) {
         Validate.notNull(threadName, "The thread name must not be null");
         Validate.notNull(threadGroupName, "The thread group name must not be null");
 
@@ -143,7 +148,7 @@ public static Collection<Thread> findThreadsByName(final String threadName, fina
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<ThreadGroup> findThreadGroupsByName(final String threadGroupName) {
+    public static @Nonnull Collection<ThreadGroup> findThreadGroupsByName(final @Nonnull String threadGroupName) {
         return findThreadGroups(new NamePredicate(threadGroupName));
     }
 
@@ -157,7 +162,7 @@ public static Collection<ThreadGroup> findThreadGroupsByName(final String thread
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<ThreadGroup> getAllThreadGroups() {
+    public static @Nonnull Collection<ThreadGroup> getAllThreadGroups() {
         return findThreadGroups(ALWAYS_TRUE_PREDICATE);
     }
 
@@ -168,7 +173,7 @@ public static Collection<ThreadGroup> getAllThreadGroups() {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static ThreadGroup getSystemThreadGroup() {
+    public static @Nonnull ThreadGroup getSystemThreadGroup() {
         ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
         while (threadGroup.getParent() != null) {
             threadGroup = threadGroup.getParent();
@@ -186,7 +191,7 @@ public static ThreadGroup getSystemThreadGroup() {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<Thread> getAllThreads() {
+    public static @Nonnull Collection<Thread> getAllThreads() {
         return findThreads(ALWAYS_TRUE_PREDICATE);
     }
 
@@ -202,7 +207,7 @@ public static Collection<Thread> getAllThreads() {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<Thread> findThreadsByName(final String threadName) {
+    public static @Nonnull Collection<Thread> findThreadsByName(final @Nonnull String threadName) {
         return findThreads(new NamePredicate(threadName));
     }
 
@@ -218,7 +223,7 @@ public static Collection<Thread> findThreadsByName(final String threadName) {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Thread findThreadById(final long threadId) {
+    public static @Nullable Thread findThreadById(final long threadId) {
         final Collection<Thread> result = findThreads(new ThreadIdPredicate(threadId));
         return result.isEmpty() ? null : result.iterator().next();
     }
@@ -269,7 +274,7 @@ public interface ThreadGroupPredicate {
     /**
      * Predicate which always returns true.
      */
-    public static final AlwaysTruePredicate ALWAYS_TRUE_PREDICATE = new AlwaysTruePredicate();
+    public static final @Nonnull AlwaysTruePredicate ALWAYS_TRUE_PREDICATE = new AlwaysTruePredicate();
 
     /**
      * A predicate implementation which always returns true.
@@ -280,12 +285,12 @@ private AlwaysTruePredicate() {
         }
 
         @Override
-        public boolean test(final ThreadGroup threadGroup) {
+        public boolean test(final @Nullable ThreadGroup threadGroup) {
             return true;
         }
 
         @Override
-        public boolean test(final Thread thread) {
+        public boolean test(final @Nullable Thread thread) {
             return true;
         }
     }
@@ -295,7 +300,7 @@ public boolean test(final Thread thread) {
      */
     public static class NamePredicate implements ThreadPredicate, ThreadGroupPredicate {
 
-        private final String name;
+        private final @Nonnull String name;
 
         /**
          * Predicate constructor
@@ -303,19 +308,19 @@ public static class NamePredicate implements ThreadPredicate, ThreadGroupPredica
          * @param name thread or threadgroup name
          * @throws IllegalArgumentException if the name is {@code null}
          */
-        public NamePredicate(final String name) {
+        public NamePredicate(final @Nonnull String name) {
             super();
             Validate.notNull(name, "The name must not be null");
             this.name = name;
         }
 
         @Override
-        public boolean test(final ThreadGroup threadGroup) {
+        public boolean test(final @Nullable ThreadGroup threadGroup) {
             return threadGroup != null && threadGroup.getName().equals(name);
         }
 
         @Override
-        public boolean test(final Thread thread) {
+        public boolean test(final @Nullable Thread thread) {
             return thread != null && thread.getName().equals(name);
         }
     }
@@ -333,7 +338,7 @@ public static class ThreadIdPredicate implements ThreadPredicate {
          * @param threadId the threadId to match
          * @throws IllegalArgumentException if the threadId is zero or negative
          */
-        public ThreadIdPredicate(final long threadId) {
+        public ThreadIdPredicate(final @Nonnegative long threadId) {
             super();
             if (threadId <= 0) {
                 throw new IllegalArgumentException("The thread id must be greater than zero");
@@ -342,7 +347,7 @@ public ThreadIdPredicate(final long threadId) {
         }
 
         @Override
-        public boolean test(final Thread thread) {
+        public boolean test(final @Nullable Thread thread) {
             return thread != null && thread.getId() == threadId;
         }
     }
@@ -359,7 +364,7 @@ public boolean test(final Thread thread) {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<Thread> findThreads(final ThreadPredicate predicate) {
+    public static @Nonnull Collection<Thread> findThreads(final @Nonnull ThreadPredicate predicate) {
         return findThreads(getSystemThreadGroup(), true, predicate);
     }
 
@@ -374,7 +379,7 @@ public static Collection<Thread> findThreads(final ThreadPredicate predicate) {
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<ThreadGroup> findThreadGroups(final ThreadGroupPredicate predicate) {
+    public static @Nonnull Collection<ThreadGroup> findThreadGroups(final @Nonnull ThreadGroupPredicate predicate) {
         return findThreadGroups(getSystemThreadGroup(), true, predicate);
     }
 
@@ -389,14 +394,18 @@ public static Collection<ThreadGroup> findThreadGroups(final ThreadGroupPredicat
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<Thread> findThreads(final ThreadGroup group, final boolean recurse, final ThreadPredicate predicate) {
+	@SuppressWarnings("null")
+	public static @Nonnull Collection<Thread> findThreads(
+    		final @Nonnull ThreadGroup group,
+    		final boolean recurse,
+    		final @Nonnull ThreadPredicate predicate) {
         Validate.notNull(group, "The group must not be null");
         Validate.notNull(predicate, "The predicate must not be null");
 
         int count = group.activeCount();
         Thread[] threads;
         do {
-            threads = new Thread[count + (count / 2) + 1]; //slightly grow the array size
+            threads = new Thread[count + count / 2 + 1]; //slightly grow the array size
             count = group.enumerate(threads, recurse);
             //return value of enumerate() must be strictly less than the array size according to javadoc
         } while (count >= threads.length);
@@ -421,14 +430,18 @@ public static Collection<Thread> findThreads(final ThreadGroup group, final bool
      * @throws  SecurityException  if the current thread cannot modify
      *          thread groups from this thread's thread group up to the system thread group
      */
-    public static Collection<ThreadGroup> findThreadGroups(final ThreadGroup group, final boolean recurse, final ThreadGroupPredicate predicate) {
+    @SuppressWarnings("null")
+	public static @Nonnull Collection<ThreadGroup> findThreadGroups(
+    		final @Nonnull ThreadGroup group,
+    		final boolean recurse,
+    		final @Nonnull ThreadGroupPredicate predicate) {
         Validate.notNull(group, "The group must not be null");
         Validate.notNull(predicate, "The predicate must not be null");
 
         int count = group.activeGroupCount();
         ThreadGroup[] threadGroups;
         do {
-            threadGroups = new ThreadGroup[count + (count / 2) + 1]; //slightly grow the array size
+            threadGroups = new ThreadGroup[count + count / 2 + 1]; //slightly grow the array size
             count = group.enumerate(threadGroups, recurse);
             //return value of enumerate() must be strictly less than the array size according to javadoc
         } while (count >= threadGroups.length);

From a6d3b80c11b1c290abec1eb0a3b5783150daacfe Mon Sep 17 00:00:00 2001
From: Alexander Guril <alexander.guril02@gmail.com>
Date: Fri, 14 Aug 2020 14:24:51 +0200
Subject: [PATCH 3/3] Update SystemUtils

---
 .../org/apache/commons/lang3/SystemUtils.java | 183 +++++++++++-------
 1 file changed, 108 insertions(+), 75 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/SystemUtils.java b/src/main/java/org/apache/commons/lang3/SystemUtils.java
index 2d6a97bf8a3..4a13dd48736 100644
--- a/src/main/java/org/apache/commons/lang3/SystemUtils.java
+++ b/src/main/java/org/apache/commons/lang3/SystemUtils.java
@@ -18,6 +18,9 @@
 
 import java.io.File;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 /**
  * <p>
  * Helpers for {@code java.lang.System}.
@@ -37,7 +40,7 @@ public class SystemUtils {
     /**
      * The prefix String for all Windows OS.
      */
-    private static final String OS_NAME_WINDOWS_PREFIX = "Windows";
+    private static final @Nonnull String OS_NAME_WINDOWS_PREFIX = "Windows";
 
     // System property constants
     // -----------------------------------------------------------------------
@@ -46,27 +49,27 @@ public class SystemUtils {
     /**
      * The System property key for the user home directory.
      */
-    private static final String USER_HOME_KEY = "user.home";
+    private static final @Nonnull String USER_HOME_KEY = "user.home";
 
     /**
      * The System property key for the user name.
      */
-    private static final String USER_NAME_KEY = "user.name";
+    private static final @Nonnull String USER_NAME_KEY = "user.name";
 
     /**
      * The System property key for the user directory.
      */
-    private static final String USER_DIR_KEY = "user.dir";
+    private static final @Nonnull String USER_DIR_KEY = "user.dir";
 
     /**
      * The System property key for the Java IO temporary directory.
      */
-    private static final String JAVA_IO_TMPDIR_KEY = "java.io.tmpdir";
+    private static final @Nonnull String JAVA_IO_TMPDIR_KEY = "java.io.tmpdir";
 
     /**
      * The System property key for the Java home directory.
      */
-    private static final String JAVA_HOME_KEY = "java.home";
+    private static final @Nonnull String JAVA_HOME_KEY = "java.home";
 
     /**
      * <p>
@@ -90,7 +93,7 @@ public class SystemUtils {
      *
      * @since 2.1
      */
-    public static final String AWT_TOOLKIT = getSystemProperty("awt.toolkit");
+    public static final @Nullable String AWT_TOOLKIT = getSystemProperty("awt.toolkit");
 
     /**
      * <p>
@@ -112,7 +115,7 @@ public class SystemUtils {
      * @since 2.0
      * @since Java 1.2
      */
-    public static final String FILE_ENCODING = getSystemProperty("file.encoding");
+    public static final @Nullable String FILE_ENCODING = getSystemProperty("file.encoding");
 
     /**
      * <p>
@@ -139,7 +142,7 @@ public class SystemUtils {
      * @since Java 1.1
      */
     @Deprecated
-    public static final String FILE_SEPARATOR = getSystemProperty("file.separator");
+    public static final @Nullable String FILE_SEPARATOR = getSystemProperty("file.separator");
 
     /**
      * <p>
@@ -157,7 +160,7 @@ public class SystemUtils {
      *
      * @since 2.1
      */
-    public static final String JAVA_AWT_FONTS = getSystemProperty("java.awt.fonts");
+    public static final @Nullable String JAVA_AWT_FONTS = getSystemProperty("java.awt.fonts");
 
     /**
      * <p>
@@ -175,7 +178,7 @@ public class SystemUtils {
      *
      * @since 2.1
      */
-    public static final String JAVA_AWT_GRAPHICSENV = getSystemProperty("java.awt.graphicsenv");
+    public static final @Nullable String JAVA_AWT_GRAPHICSENV = getSystemProperty("java.awt.graphicsenv");
 
     /**
      * <p>
@@ -196,7 +199,7 @@ public class SystemUtils {
      * @since 2.1
      * @since Java 1.4
      */
-    public static final String JAVA_AWT_HEADLESS = getSystemProperty("java.awt.headless");
+    public static final @Nullable String JAVA_AWT_HEADLESS = getSystemProperty("java.awt.headless");
 
     /**
      * <p>
@@ -214,7 +217,7 @@ public class SystemUtils {
      *
      * @since 2.1
      */
-    public static final String JAVA_AWT_PRINTERJOB = getSystemProperty("java.awt.printerjob");
+    public static final @Nullable String JAVA_AWT_PRINTERJOB = getSystemProperty("java.awt.printerjob");
 
     /**
      * <p>
@@ -232,7 +235,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String JAVA_CLASS_PATH = getSystemProperty("java.class.path");
+    public static final @Nullable String JAVA_CLASS_PATH = getSystemProperty("java.class.path");
 
     /**
      * <p>
@@ -250,7 +253,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String JAVA_CLASS_VERSION = getSystemProperty("java.class.version");
+    public static final @Nullable String JAVA_CLASS_VERSION = getSystemProperty("java.class.version");
 
     /**
      * <p>
@@ -269,7 +272,7 @@ public class SystemUtils {
      *
      * @since Java 1.2. Not used in Sun versions after 1.2.
      */
-    public static final String JAVA_COMPILER = getSystemProperty("java.compiler");
+    public static final @Nullable String JAVA_COMPILER = getSystemProperty("java.compiler");
 
     /**
      * <p>
@@ -287,7 +290,7 @@ public class SystemUtils {
      *
      * @since Java 1.4
      */
-    public static final String JAVA_ENDORSED_DIRS = getSystemProperty("java.endorsed.dirs");
+    public static final @Nullable String JAVA_ENDORSED_DIRS = getSystemProperty("java.endorsed.dirs");
 
     /**
      * <p>
@@ -305,7 +308,7 @@ public class SystemUtils {
      *
      * @since Java 1.3
      */
-    public static final String JAVA_EXT_DIRS = getSystemProperty("java.ext.dirs");
+    public static final @Nullable String JAVA_EXT_DIRS = getSystemProperty("java.ext.dirs");
 
     /**
      * <p>
@@ -323,7 +326,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String JAVA_HOME = getSystemProperty(JAVA_HOME_KEY);
+    public static final @Nullable String JAVA_HOME = getSystemProperty(JAVA_HOME_KEY);
 
     /**
      * <p>
@@ -341,7 +344,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_IO_TMPDIR = getSystemProperty(JAVA_IO_TMPDIR_KEY);
+    public static final @Nullable String JAVA_IO_TMPDIR = getSystemProperty(JAVA_IO_TMPDIR_KEY);
 
     /**
      * <p>
@@ -359,7 +362,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_LIBRARY_PATH = getSystemProperty("java.library.path");
+    public static final @Nullable String JAVA_LIBRARY_PATH = getSystemProperty("java.library.path");
 
     /**
      * <p>
@@ -378,7 +381,7 @@ public class SystemUtils {
      * @since 2.0
      * @since Java 1.3
      */
-    public static final String JAVA_RUNTIME_NAME = getSystemProperty("java.runtime.name");
+    public static final @Nullable String JAVA_RUNTIME_NAME = getSystemProperty("java.runtime.name");
 
     /**
      * <p>
@@ -397,7 +400,7 @@ public class SystemUtils {
      * @since 2.0
      * @since Java 1.3
      */
-    public static final String JAVA_RUNTIME_VERSION = getSystemProperty("java.runtime.version");
+    public static final @Nullable String JAVA_RUNTIME_VERSION = getSystemProperty("java.runtime.version");
 
     /**
      * <p>
@@ -415,7 +418,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_SPECIFICATION_NAME = getSystemProperty("java.specification.name");
+    public static final @Nullable String JAVA_SPECIFICATION_NAME = getSystemProperty("java.specification.name");
 
     /**
      * <p>
@@ -433,7 +436,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_SPECIFICATION_VENDOR = getSystemProperty("java.specification.vendor");
+    public static final @Nullable String JAVA_SPECIFICATION_VENDOR = getSystemProperty("java.specification.vendor");
 
     /**
      * <p>
@@ -451,8 +454,9 @@ public class SystemUtils {
      *
      * @since Java 1.3
      */
-    public static final String JAVA_SPECIFICATION_VERSION = getSystemProperty("java.specification.version");
-    private static final JavaVersion JAVA_SPECIFICATION_VERSION_AS_ENUM = JavaVersion.get(JAVA_SPECIFICATION_VERSION);
+    public static final @Nullable String JAVA_SPECIFICATION_VERSION = getSystemProperty("java.specification.version");
+    
+    private static final @Nullable JavaVersion JAVA_SPECIFICATION_VERSION_AS_ENUM = JavaVersion.get(JAVA_SPECIFICATION_VERSION);
 
     /**
      * <p>
@@ -471,7 +475,7 @@ public class SystemUtils {
      * @since 2.1
      * @since Java 1.4
      */
-    public static final String JAVA_UTIL_PREFS_PREFERENCES_FACTORY =
+    public static final @Nullable String JAVA_UTIL_PREFS_PREFERENCES_FACTORY =
         getSystemProperty("java.util.prefs.PreferencesFactory");
 
     /**
@@ -490,7 +494,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String JAVA_VENDOR = getSystemProperty("java.vendor");
+    public static final @Nullable String JAVA_VENDOR = getSystemProperty("java.vendor");
 
     /**
      * <p>
@@ -508,7 +512,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String JAVA_VENDOR_URL = getSystemProperty("java.vendor.url");
+    public static final @Nullable String JAVA_VENDOR_URL = getSystemProperty("java.vendor.url");
 
     /**
      * <p>
@@ -526,7 +530,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String JAVA_VERSION = getSystemProperty("java.version");
+    public static final @Nullable String JAVA_VERSION = getSystemProperty("java.version");
 
     /**
      * <p>
@@ -545,7 +549,7 @@ public class SystemUtils {
      * @since 2.0
      * @since Java 1.2
      */
-    public static final String JAVA_VM_INFO = getSystemProperty("java.vm.info");
+    public static final @Nullable String JAVA_VM_INFO = getSystemProperty("java.vm.info");
 
     /**
      * <p>
@@ -563,7 +567,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_VM_NAME = getSystemProperty("java.vm.name");
+    public static final @Nullable String JAVA_VM_NAME = getSystemProperty("java.vm.name");
 
     /**
      * <p>
@@ -581,7 +585,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_VM_SPECIFICATION_NAME = getSystemProperty("java.vm.specification.name");
+    public static final @Nullable String JAVA_VM_SPECIFICATION_NAME = getSystemProperty("java.vm.specification.name");
 
     /**
      * <p>
@@ -599,7 +603,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_VM_SPECIFICATION_VENDOR = getSystemProperty("java.vm.specification.vendor");
+    public static final @Nullable String JAVA_VM_SPECIFICATION_VENDOR = getSystemProperty("java.vm.specification.vendor");
 
     /**
      * <p>
@@ -617,7 +621,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_VM_SPECIFICATION_VERSION = getSystemProperty("java.vm.specification.version");
+    public static final @Nullable String JAVA_VM_SPECIFICATION_VERSION = getSystemProperty("java.vm.specification.version");
 
     /**
      * <p>
@@ -635,7 +639,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_VM_VENDOR = getSystemProperty("java.vm.vendor");
+    public static final @Nullable String JAVA_VM_VENDOR = getSystemProperty("java.vm.vendor");
 
     /**
      * <p>
@@ -653,7 +657,7 @@ public class SystemUtils {
      *
      * @since Java 1.2
      */
-    public static final String JAVA_VM_VERSION = getSystemProperty("java.vm.version");
+    public static final @Nullable String JAVA_VM_VERSION = getSystemProperty("java.vm.version");
 
     /**
      * <p>
@@ -673,7 +677,7 @@ public class SystemUtils {
      * @since Java 1.1
      */
     @Deprecated
-    public static final String LINE_SEPARATOR = getSystemProperty("line.separator");
+    public static final @Nullable String LINE_SEPARATOR = getSystemProperty("line.separator");
 
     /**
      * <p>
@@ -691,7 +695,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String OS_ARCH = getSystemProperty("os.arch");
+    public static final @Nullable String OS_ARCH = getSystemProperty("os.arch");
 
     /**
      * <p>
@@ -709,7 +713,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String OS_NAME = getSystemProperty("os.name");
+    public static final @Nullable String OS_NAME = getSystemProperty("os.name");
 
     /**
      * <p>
@@ -727,7 +731,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String OS_VERSION = getSystemProperty("os.version");
+    public static final @Nullable String OS_VERSION = getSystemProperty("os.version");
 
     /**
      * <p>
@@ -748,7 +752,7 @@ public class SystemUtils {
      * @since Java 1.1
      */
     @Deprecated
-    public static final String PATH_SEPARATOR = getSystemProperty("path.separator");
+    public static final @Nullable String PATH_SEPARATOR = getSystemProperty("path.separator");
 
     /**
      * <p>
@@ -768,7 +772,7 @@ public class SystemUtils {
      * @since 2.0
      * @since Java 1.2
      */
-    public static final String USER_COUNTRY = getSystemProperty("user.country") == null ?
+    public static final @Nullable String USER_COUNTRY = getSystemProperty("user.country") == null ?
             getSystemProperty("user.region") : getSystemProperty("user.country");
 
     /**
@@ -787,7 +791,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String USER_DIR = getSystemProperty(USER_DIR_KEY);
+    public static final @Nullable String USER_DIR = getSystemProperty(USER_DIR_KEY);
 
     /**
      * <p>
@@ -805,7 +809,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String USER_HOME = getSystemProperty(USER_HOME_KEY);
+    public static final @Nullable String USER_HOME = getSystemProperty(USER_HOME_KEY);
 
     /**
      * <p>
@@ -824,7 +828,7 @@ public class SystemUtils {
      * @since 2.0
      * @since Java 1.2
      */
-    public static final String USER_LANGUAGE = getSystemProperty("user.language");
+    public static final @Nullable String USER_LANGUAGE = getSystemProperty("user.language");
 
     /**
      * <p>
@@ -842,7 +846,7 @@ public class SystemUtils {
      *
      * @since Java 1.1
      */
-    public static final String USER_NAME = getSystemProperty(USER_NAME_KEY);
+    public static final @Nullable String USER_NAME = getSystemProperty(USER_NAME_KEY);
 
     /**
      * <p>
@@ -860,7 +864,7 @@ public class SystemUtils {
      *
      * @since 2.1
      */
-    public static final String USER_TIMEZONE = getSystemProperty("user.timezone");
+    public static final @Nullable String USER_TIMEZONE = getSystemProperty("user.timezone");
 
     // Java version checks
     // -----------------------------------------------------------------------
@@ -1568,7 +1572,7 @@ public class SystemUtils {
      * @see System#getProperty(String)
      * @since 2.1
      */
-    public static File getJavaHome() {
+    public static @Nonnull File getJavaHome() {
         return new File(System.getProperty(JAVA_HOME_KEY));
     }
 
@@ -1583,7 +1587,7 @@ public static File getJavaHome() {
      * @return the host name. Will be {@code null} if the environment variable is not defined.
      * @since 3.6
      */
-    public static String getHostName() {
+    public static @Nullable String getHostName() {
         return IS_OS_WINDOWS ? System.getenv("COMPUTERNAME") : System.getenv("HOSTNAME");
     }
 
@@ -1598,7 +1602,7 @@ public static String getHostName() {
      * @see System#getProperty(String)
      * @since 2.1
      */
-    public static File getJavaIoTmpDir() {
+    public static @Nonnull File getJavaIoTmpDir() {
         return new File(System.getProperty(JAVA_IO_TMPDIR_KEY));
     }
 
@@ -1610,8 +1614,13 @@ public static File getJavaIoTmpDir() {
      * @param versionPrefix the prefix for the java version
      * @return true if matches, or false if not or can't determine
      */
-    private static boolean getJavaVersionMatches(final String versionPrefix) {
-        return isJavaVersionMatch(JAVA_SPECIFICATION_VERSION, versionPrefix);
+    private static boolean getJavaVersionMatches(final @Nonnull String versionPrefix) {
+        final String javaSpecVersion = JAVA_SPECIFICATION_VERSION;
+		if (javaSpecVersion != null) {
+			return isJavaVersionMatch(javaSpecVersion, versionPrefix);
+		} else {
+			return false;
+		}
     }
 
     /**
@@ -1621,8 +1630,13 @@ private static boolean getJavaVersionMatches(final String versionPrefix) {
      * @param osVersionPrefix the prefix for the version
      * @return true if matches, or false if not or can't determine
      */
-    private static boolean getOsMatches(final String osNamePrefix, final String osVersionPrefix) {
-        return isOSMatch(OS_NAME, OS_VERSION, osNamePrefix, osVersionPrefix);
+    private static boolean getOsMatches(final @Nonnull String osNamePrefix, final @Nonnull String osVersionPrefix) {
+    	final String osName = OS_NAME;
+    	final String osVersion = OS_VERSION;
+    	if(osName == null || osVersion == null) {
+    		return false;
+    	}
+        return isOSMatch(osName, osVersion, osNamePrefix, osVersionPrefix);
     }
 
     /**
@@ -1631,8 +1645,13 @@ private static boolean getOsMatches(final String osNamePrefix, final String osVe
      * @param osNamePrefix the prefix for the OS name
      * @return true if matches, or false if not or can't determine
      */
-    private static boolean getOsMatchesName(final String osNamePrefix) {
-        return isOSNameMatch(OS_NAME, osNamePrefix);
+    private static boolean getOsMatchesName(final @Nonnull String osNamePrefix) {
+        final String osName = OS_NAME;
+		if (osName != null) {
+			return isOSNameMatch(osName, osNamePrefix);
+		} else {
+			return false;
+		}
     }
 
     // -----------------------------------------------------------------------
@@ -1648,7 +1667,7 @@ private static boolean getOsMatchesName(final String osNamePrefix) {
      * @param property the system property name
      * @return the system property value or {@code null} if a security problem occurs
      */
-    private static String getSystemProperty(final String property) {
+    private static @Nullable String getSystemProperty(final @Nonnull String property) {
         try {
             return System.getProperty(property);
         } catch (final SecurityException ex) {
@@ -1675,7 +1694,7 @@ private static String getSystemProperty(final String property) {
      * @return the environment variable value or {@code defaultValue} if a security problem occurs
      * @since 3.8
      */
-    public static String getEnvironmentVariable(final String name, final String defaultValue) {
+    public static @Nullable String getEnvironmentVariable(final @Nonnull String name, final @Nullable String defaultValue) {
         try {
             final String value = System.getenv(name);
             return value == null ? defaultValue : value;
@@ -1697,7 +1716,7 @@ public static String getEnvironmentVariable(final String name, final String defa
      * @see System#getProperty(String)
      * @since 2.1
      */
-    public static File getUserDir() {
+    public static @Nonnull File getUserDir() {
         return new File(System.getProperty(USER_DIR_KEY));
     }
 
@@ -1712,7 +1731,7 @@ public static File getUserDir() {
      * @see System#getProperty(String)
      * @since 2.1
      */
-    public static File getUserHome() {
+    public static @Nonnull File getUserHome() {
         return new File(System.getProperty(USER_HOME_KEY));
     }
 
@@ -1727,7 +1746,7 @@ public static File getUserHome() {
      * @see System#getProperty(String)
      * @since 3.10
      */
-    public static String getUserName() {
+    public static @Nullable String getUserName() {
         return System.getProperty(USER_NAME_KEY);
     }
 
@@ -1743,7 +1762,7 @@ public static String getUserName() {
      * @see System#getProperty(String)
      * @since 3.10
      */
-    public static String getUserName(final String defaultValue) {
+    public static @Nullable String getUserName(final @Nullable String defaultValue) {
         return System.getProperty(USER_NAME_KEY, defaultValue);
     }
 
@@ -1768,8 +1787,13 @@ public static boolean isJavaAwtHeadless() {
      * @param requiredVersion the required version, for example 1.31f
      * @return {@code true} if the actual version is equal or greater than the required version
      */
-    public static boolean isJavaVersionAtLeast(final JavaVersion requiredVersion) {
-        return JAVA_SPECIFICATION_VERSION_AS_ENUM.atLeast(requiredVersion);
+    public static boolean isJavaVersionAtLeast(final @Nonnull JavaVersion requiredVersion) {
+        final JavaVersion javaSpecVersion = JAVA_SPECIFICATION_VERSION_AS_ENUM;
+		if (javaSpecVersion != null) {
+			return javaSpecVersion.atLeast(requiredVersion);
+		} else {
+			return false;
+		}
     }
 
     /**
@@ -1784,8 +1808,13 @@ public static boolean isJavaVersionAtLeast(final JavaVersion requiredVersion) {
      * @return {@code true} if the actual version is equal or greater than the required version
      * @since 3.9
      */
-    public static boolean isJavaVersionAtMost(final JavaVersion requiredVersion) {
-        return JAVA_SPECIFICATION_VERSION_AS_ENUM.atMost(requiredVersion);
+    public static boolean isJavaVersionAtMost(final @Nonnull JavaVersion requiredVersion) {
+        final JavaVersion javaSpecVersion = JAVA_SPECIFICATION_VERSION_AS_ENUM;
+		if (javaSpecVersion != null) {
+			return javaSpecVersion.atMost(requiredVersion);
+		} else {
+			return false;
+		}
     }
 
     /**
@@ -1800,8 +1829,8 @@ public static boolean isJavaVersionAtMost(final JavaVersion requiredVersion) {
      * @param versionPrefix the prefix for the expected Java version
      * @return true if matches, or false if not or can't determine
      */
-    static boolean isJavaVersionMatch(final String version, final String versionPrefix) {
-        if (version == null) {
+    static boolean isJavaVersionMatch(final @Nonnull String version, final @Nonnull String versionPrefix) {
+        if (StringUtils.isEmpty(version)) {
             return false;
         }
         return version.startsWith(versionPrefix);
@@ -1819,8 +1848,12 @@ static boolean isJavaVersionMatch(final String version, final String versionPref
      * @param osVersionPrefix the prefix for the expected OS version
      * @return true if matches, or false if not or can't determine
      */
-    static boolean isOSMatch(final String osName, final String osVersion, final String osNamePrefix, final String osVersionPrefix) {
-        if (osName == null || osVersion == null) {
+    static boolean isOSMatch(
+    		final @Nonnull String osName,
+    		final @Nonnull String osVersion,
+    		final @Nonnull String osNamePrefix,
+    		final @Nonnull String osVersionPrefix) {
+        if (StringUtils.isEmpty(osName) || StringUtils.isEmpty(osVersion)) {
             return false;
         }
         return isOSNameMatch(osName, osNamePrefix) && isOSVersionMatch(osVersion, osVersionPrefix);
@@ -1836,8 +1869,8 @@ static boolean isOSMatch(final String osName, final String osVersion, final Stri
      * @param osNamePrefix the prefix for the expected OS name
      * @return true if matches, or false if not or can't determine
      */
-    static boolean isOSNameMatch(final String osName, final String osNamePrefix) {
-        if (osName == null) {
+    static boolean isOSNameMatch(final @Nonnull String osName, final @Nonnull String osNamePrefix) {
+        if (StringUtils.isEmpty(osName)) {
             return false;
         }
         return osName.startsWith(osNamePrefix);
@@ -1853,7 +1886,7 @@ static boolean isOSNameMatch(final String osName, final String osNamePrefix) {
      * @param osVersionPrefix the prefix for the expected OS version
      * @return true if matches, or false if not or can't determine
      */
-    static boolean isOSVersionMatch(final String osVersion, final String osVersionPrefix) {
+    static boolean isOSVersionMatch(final @Nonnull String osVersion, final @Nonnull String osVersionPrefix) {
         if (StringUtils.isEmpty(osVersion)) {
             return false;
         }