Fix print idempotency for Javadoc <pre><code> blocks on Java 25

[knutwannheden]

Motivation

Parsing Javadoc comments containing <pre><code> blocks with a newline after the opening tag failed the parser's print idempotency check on Java 25 (but not on Java 8/11/17/21). This surfaced against Google Dagger in a Moderne CLI run — 18 Java files in google/dagger failed to parse with IllegalStateException: ... is not print idempotent, all of them Javadoc comments in the common style:

/**
 * <pre><code>
 *   class Outer {
 *     static class Inner {}
 *   }
 * </code></pre>
 */

Root cause: Java 25's DocCommentTree strips leading whitespace (including newlines) from text nodes, so the raw source has \n characters that the DCText / DCRawText body does not. In ReloadableJava25JavadocVisitor.visitText, the else branch blindly advanced the cursor past these \n characters without emitting a corresponding LineBreak. The unconsumed LineBreak then got dumped at the end of the comment by the trailing-lineBreaks flush, producing a stray * line before the closing */.

Summary

• ReloadableJava25JavadocVisitor.visitText: before processing each character from the text node, consume any \n in the source that is missing from the node and emit the corresponding LineBreak.
• Add four parser idempotency tests in JavadocTest covering variants of <pre><code> blocks (newline after opening tag, two consecutive blocks, blocks containing {@literal} inline tags, block starting on the same line as preceding text).

Test plan

• ./gradlew :rewrite-java-25:test :rewrite-java-25:compatibilityTest — all green, including the four new preCodeBlock* tests
• CI across all Java versions