Fix StringUtilities.capitalise throwing on leading whitespace

[dsavy4]

Problem

StringUtilities.capitalise throws StringIndexOutOfBoundsException when the input has leading whitespace.

words.split("\\s+") keeps an empty leading token when the string starts with whitespace (Java only trims trailing empty tokens). The per-word mapper then calls charAt(0) and substring(1) on that empty token and throws.

StringUtilities.capitalise(" hello"); // throws, expected "Hello"
StringUtilities.capitalise("   ");     // throws, expected ""

Fix

Filter out empty tokens before mapping:

.stream(words.split("\\s+"))
.filter(w -> !w.isEmpty())
.map(...)

Whitespace-only input now returns "", which matches the intent already noted in the existing test comments (" " => ""). All existing cases are unchanged, since none of them start with whitespace.

Tests

Added leadingWhitespace and onlyWhitespace cases to StringUtilities_capitaliseTest. Verified the fix independently with the JDK (old throws, fixed returns Hello / Hello World / "", existing cases unchanged).

[linux-foundation-easycla]

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• ✅ login: dsavy4 / name: Dmitry Savy (50154c3)

[dsavy4]

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Signed and accepted