Trim down PR apache#2506: Remove configuration and statistics

This commit removes the following components from the comprehensive PR apache#2506:
- CacheConfigurationResolver and related configuration classes
- CacheStatistics and related statistics tracking
- Cache configuration parsing and system property handling
- Factory methods from InputSource and InputLocation (merge methods)
- Complex object pooling configuration (keeping only Dependency pooling)

Remaining work:
- Fix compilation errors for missing interfaces
- Adapt to current master branch API structure
- Ensure all tests pass

This trimmed version keeps the core cache improvements while removing
the configuration complexity that's not needed for the 4.0.x branch.

# Conflicts:
#	impl/maven-impl/src/main/java/org/apache/maven/impl/cache/DefaultRequestCache.java
#	impl/maven-impl/src/main/java/org/apache/maven/impl/model/DefaultModelObjectPool.java
#	impl/maven-impl/src/test/java/org/apache/maven/impl/cache/ReferenceTypeStatisticsTest.java

Author: gnodet

api/maven-api-core/src/main/java/org/apache/maven/api/Constants.java

@@ -638,66 +638,5 @@ public final class Constants {
      */
     public static final String MAVEN_LOGGER_LOG_PREFIX = MAVEN_LOGGER_PREFIX + "log.";
 
-    /**
-     * User property key for cache configuration.
-     *
-     * @since 4.1.0
-     */
-    public static final String MAVEN_CACHE_CONFIG_PROPERTY = "maven.cache.config";
-
-    /**
-     * User property to enable cache statistics display at the end of the build.
-     * When set to true, detailed cache statistics including hit/miss ratios,
-     * request type breakdowns, and retention policy effectiveness will be displayed
-     * when the build completes.
-     *
-     * @since 4.1.0
-     */
-    @Config(type = "java.lang.Boolean", defaultValue = "false")
-    public static final String MAVEN_CACHE_STATS = "maven.cache.stats";
-
-    /**
-     * User property to configure separate reference types for cache keys and values.
-     * Format: "key:value" where key and value can be NONE, SOFT, WEAK, or HARD.
-     * Examples:
-     * - "HARD:SOFT" - Keep keys strongly referenced, allow values to be garbage collected under memory pressure
-     * - "WEAK:WEAK" - Allow both keys and values to be garbage collected aggressively
-     * - "SOFT:HARD" - Allow keys to be GC'd under memory pressure, keep values strongly referenced
-     *
-     * This enables fine-grained analysis of cache misses caused by key vs value evictions.
-     *
-     * @since 4.1.0
-     */
-    public static final String MAVEN_CACHE_KEY_VALUE_REFS = "maven.cache.keyValueRefs";
-
-    /**
-     * User property key for configuring which object types are pooled by ModelObjectProcessor.
-     * Value should be a comma-separated list of simple class names (e.g., "Dependency,Plugin,Build").
-     * Default is "Dependency" for backward compatibility.
-     *
-     * @since 4.1.0
-     */
-    @Config(defaultValue = "Dependency")
-    public static final String MAVEN_MODEL_PROCESSOR_POOLED_TYPES = "maven.model.processor.pooledTypes";
-
-    /**
-     * User property key for configuring the default reference type used by ModelObjectProcessor.
-     * Valid values are: "SOFT", "HARD", "WEAK", "NONE".
-     * Default is "HARD" for optimal performance.
-     *
-     * @since 4.1.0
-     */
-    @Config(defaultValue = "HARD")
-    public static final String MAVEN_MODEL_PROCESSOR_REFERENCE_TYPE = "maven.model.processor.referenceType";
-
-    /**
-     * User property key prefix for configuring per-object-type reference types.
-     * Format: maven.model.processor.referenceType.{ClassName} = {ReferenceType}
-     * Example: maven.model.processor.referenceType.Dependency = SOFT
-     *
-     * @since 4.1.0
-     */
-    public static final String MAVEN_MODEL_PROCESSOR_REFERENCE_TYPE_PREFIX = "maven.model.processor.referenceType.";
-
     private Constants() {}
 }

api/maven-api-model/src/main/java/org/apache/maven/api/model/InputLocation.java

@@ -84,102 +84,25 @@ public static InputLocation of() {
         return EMPTY;
     }
 
-    /**
-     * Creates a new InputLocation with the specified source.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param source the input source
-     * @return a new InputLocation instance
-     */
     public static InputLocation of(InputSource source) {
-        return ModelObjectProcessor.processObject(new InputLocation(source));
+        return new InputLocation(0, 0, source);
     }
 
-    /**
-     * Creates a new InputLocation with the specified line and column numbers.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param lineNumber the line number
-     * @param columnNumber the column number
-     * @return a new InputLocation instance
-     */
     public static InputLocation of(int lineNumber, int columnNumber) {
-        return ModelObjectProcessor.processObject(new InputLocation(lineNumber, columnNumber));
+        return new InputLocation(lineNumber, columnNumber);
     }
 
-    /**
-     * Creates a new InputLocation with the specified line number, column number, and source.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param lineNumber the line number
-     * @param columnNumber the column number
-     * @param source the input source
-     * @return a new InputLocation instance
-     */
     public static InputLocation of(int lineNumber, int columnNumber, InputSource source) {
-        return ModelObjectProcessor.processObject(new InputLocation(lineNumber, columnNumber, source));
+        return new InputLocation(lineNumber, columnNumber, source);
     }
 
-    /**
-     * Creates a new InputLocation with the specified line number, column number, source, and self location key.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param lineNumber the line number
-     * @param columnNumber the column number
-     * @param source the input source
-     * @param selfLocationKey the self location key
-     * @return a new InputLocation instance
-     */
     public static InputLocation of(int lineNumber, int columnNumber, InputSource source, Object selfLocationKey) {
-        return ModelObjectProcessor.processObject(new InputLocation(lineNumber, columnNumber, source, selfLocationKey));
+        return new InputLocation(lineNumber, columnNumber, source, selfLocationKey);
     }
 
-    /**
-     * Creates a new InputLocation with the specified line number, column number, source, and locations map.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param lineNumber the line number
-     * @param columnNumber the column number
-     * @param source the input source
-     * @param locations the locations map
-     * @return a new InputLocation instance
-     */
     public static InputLocation of(
             int lineNumber, int columnNumber, InputSource source, Map<Object, InputLocation> locations) {
-        return ModelObjectProcessor.processObject(new InputLocation(lineNumber, columnNumber, source, locations));
-    }
-
-    public int getLineNumber() {
-        return lineNumber;
-    }
-
-    public int getColumnNumber() {
-        return columnNumber;
-    }
-
-    public InputSource getSource() {
-        return source;
-    }
-
-    @Override
-    public InputLocation getLocation(Object key) {
-        return locations != null ? locations.get(key) : null;
-    }
-
-    public Map<Object, InputLocation> getLocations() {
-        return locations;
-    }
-
-    /**
-     * Gets the parent InputLocation where this InputLocation may have been imported from.
-     * Can return {@code null}.
-     *
-     * @return InputLocation
-     * @since 4.0.0
-     */
-    @Override
-    public InputLocation getImportedFrom() {
-        return importedFrom;
+        return new InputLocation(lineNumber, columnNumber, source, locations);
     }
 
     /**
@@ -211,7 +134,7 @@ public static InputLocation merge(InputLocation target, InputLocation source, bo
         }
 
         return new InputLocation(-1, -1, InputSource.merge(source.getSource(), target.getSource()), locations);
-    } // -- InputLocation merge( InputLocation, InputLocation, boolean )
+    }
 
     /**
      * Merges the {@code source} location into the {@code target} location.
@@ -250,7 +173,40 @@ public static InputLocation merge(InputLocation target, InputLocation source, Co
         }
 
         return new InputLocation(-1, -1, InputSource.merge(source.getSource(), target.getSource()), locations);
-    } // -- InputLocation merge( InputLocation, InputLocation, java.util.Collection )
+    }
+
+    public int getLineNumber() {
+        return lineNumber;
+    }
+
+    public int getColumnNumber() {
+        return columnNumber;
+    }
+
+    public InputSource getSource() {
+        return source;
+    }
+
+    @Override
+    public InputLocation getLocation(Object key) {
+        return locations != null ? locations.get(key) : null;
+    }
+
+    public Map<Object, InputLocation> getLocations() {
+        return locations;
+    }
+
+    /**
+     * Gets the parent InputLocation where this InputLocation may have been imported from.
+     * Can return {@code null}.
+     *
+     * @return InputLocation
+     * @since 4.0.0
+     */
+    @Override
+    public InputLocation getImportedFrom() {
+        return importedFrom;
+    }
 
     @Override
     public boolean equals(Object o) {

api/maven-api-model/src/main/java/org/apache/maven/api/model/InputSource.java

@@ -63,42 +63,6 @@ public InputSource(Collection<InputSource> inputs) {
 
     // Factory methods
 
-    /**
-     * Creates a new InputSource with the specified model ID and location.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param modelId the model ID
-     * @param location the location
-     * @return a new InputSource instance
-     */
-    public static InputSource of(String modelId, String location) {
-        return ModelObjectProcessor.processObject(new InputSource(modelId, location));
-    }
-
-    /**
-     * Creates a new InputSource with the specified model ID, location, and imported from location.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param modelId the model ID
-     * @param location the location
-     * @param importedFrom the imported from location
-     * @return a new InputSource instance
-     */
-    public static InputSource of(String modelId, String location, InputLocation importedFrom) {
-        return ModelObjectProcessor.processObject(new InputSource(modelId, location, importedFrom));
-    }
-
-    /**
-     * Creates a new InputSource from a collection of input sources.
-     * The created instance is processed through ModelObjectProcessor for optimization.
-     *
-     * @param inputs the collection of input sources
-     * @return a new InputSource instance
-     */
-    public static InputSource of(Collection<InputSource> inputs) {
-        return ModelObjectProcessor.processObject(new InputSource(inputs));
-    }
-
     /**
      * Get the path/URL of the POM or {@code null} if unknown.
      *
@@ -165,6 +129,56 @@ public String toString() {
         return getModelId() + " " + getLocation();
     }
 
+    /**
+     * Creates a new InputSource with the specified model ID and location.
+     *
+     * @param modelId the model ID
+     * @param location the location
+     * @return a new InputSource
+     */
+    public static InputSource of(String modelId, String location) {
+        return new InputSource(modelId, location);
+    }
+
+    /**
+     * Creates a new InputSource with the specified location.
+     *
+     * @param location the location
+     * @return a new InputSource
+     */
+    public static InputSource of(String location) {
+        return new InputSource(null, location);
+    }
+
+    /**
+     * Creates a new InputSource with the specified model ID, location, and imported from location.
+     *
+     * @param modelId the model ID
+     * @param location the location
+     * @param importedFrom the imported from location
+     * @return a new InputSource
+     */
+    public static InputSource of(String modelId, String location, InputLocation importedFrom) {
+        return new InputSource(modelId, location, importedFrom);
+    }
+
+    /**
+     * Creates a new InputSource from a collection of input sources.
+     *
+     * @param inputs the collection of input sources
+     * @return a new InputSource
+     */
+    public static InputSource of(Collection<InputSource> inputs) {
+        return new InputSource(inputs);
+    }
+
+    /**
+     * Merges two InputSource instances.
+     *
+     * @param src1 the first input source
+     * @param src2 the second input source
+     * @return a new merged InputSource
+     */
     public static InputSource merge(InputSource src1, InputSource src2) {
         return new InputSource(
                 Stream.concat(src1.sources(), src2.sources()).distinct().toList());