Keep a javadoc {@snippet} as it is written

[abashev]

Brings over google/google-java-format#1141, a fix from google-java-format 1.24.

The bug

With javadoc formatting on (JavaFormatterOptions.formatJavadoc(true)), the lines of a {@snippet ...} tag were reflowed like prose:

/**
 * Example usage:
 *
 * <p>{@snippet : int x = 1; foo(x, y); // keep this }
 *
 * <p>Done.
 */

The code inside came out on one line, <p> in front of it, and a // comment in the snippet swallowed the closing brace. The lexer treated the snippet as any other inline tag, whose contents are joined and wrapped.

From upstream, with the author kept

• Avoid mangling {@snippet ...}. google/google-java-format#1141 by cpovirk (Chris Povirk), commit authored by them: {@snippet that starts an inline tag is its own token, everything up to its closing brace keeps its newlines and spaces as inside <pre>, and the writer puts a blank line before and after the snippet. Nothing inside the snippet is reformatted. The tests blankLinesAroundSnippetAndNoMangling and notASnippetUnlessOuterTag come with it.
• Adapted to this lexer, which keeps inline tags as INLINE_TAG_OPEN and INLINE_TAG_CLOSE tokens (Keep javadoc inline tags like {@link ...} together palantir/palantir-java-format#125): a {@snippet inside another inline tag is an ordinary inline tag here, as upstream's is an ordinary literal.

Added here

• snippetKeepsCommentsAndIndentation: a snippet with indented code and a // @highlight markup comment stays exactly as written.

Checked

• The three tests fail on main and pass with the change.
• ./gradlew :open-java-format:test on JDK 21: 1500 tests, all green.
• Javadoc formatting is off unless JavaFormatterOptions asks for it, and the lexer only runs then, so the default output and the JDK corpus are unchanged by construction.