Do not hug a lambda on the first line of an if/while/for/switch/try header #181

Upstream: google/google-java-format#1507
Kind: idea | Priority: low

google-java-format#1507 (merged 2026-10-29, copybara export) stops hugging block lambdas that start on the first line of a statement header followed by a body (if, while, for, enhanced for, switch, synchronized, try-with-resources). Otherwise the lambda body lands at the same indent as the statement body and the closing })) { hides where the header ends. Expression lambdas break before the parameter instead. Hugging still applies on continuation lines of the header and in do-while conditions. Upstream adds a zero-width HeaderMark to its layout IR for this.

Why it matters: it is the third recent hugging change after google-java-format#1489 and google-java-format#1499, and the only one that targets the if (x.anyMatch(c -> { readability problem. Our palantir-derived engine formats lambdas differently, so the question is whether we have this problem at all.

Affected files in our repo:

• open-java-format/src/main/java/com/palantir/javaformat/java/JavaInputAstVisitor.java (lambda and argument handling)
• open-java-format/src/test/resources/com/palantir/javaformat/java/testdata/palantir-chains-lambdas.input and .output

Suggested action: watch / investigate. Run a block lambda inside an if condition through our formatter; adopt only if the body indent equals the statement body indent. Examples: not available - the upstream golden diff was not usable to derive our output.

Filed from an upstream-watch ticket after manual review.