google-java-format fails on Java 25: DeferredDiagnosticHandler.getDiagnostics() removed

[tedberg]

Environment

• openapi-processor-spring: 2026.2
• openapi-processor-maven-plugin: 2026.1
• openapi-processor-core: 2026.2 (bundles google-java-format 1.24.0)
• JDK: OpenJDK 25.0.2 (Corretto)

Problem

When format-code: true is set in mapping.yaml, the plugin fails with:

java.lang.NoSuchMethodError: 'java.util.Queue
com.sun.tools.javac.util.Log$DeferredDiagnosticHandler.getDiagnostics()'

DeferredDiagnosticHandler.getDiagnostics() was removed from javac internals
in Java 25. google-java-format 1.24.0 (bundled in openapi-processor-core 2026.2)
calls this method, causing a hard failure — not an accessibility issue, so
--add-opens won't help.

Workaround

Set format-code: false in mapping.yaml and format generated sources separately.

Fix

Update the bundled google-java-format to a version that supports Java 25. Also consider the palantirJavaFormat plugin. This one extends the one from google and it seems to already be Java 25 compatible.

[hauner]

you could try format: eclipse instead of format: google (which is the same as format: true)

the eclipse formatter does not depend on internal jdk stuff.

It is currently using an older google format because the processor build is using java 11 and google format versions newer than 1.24 require at least java 17.

Anyway, I will also update the build jdk so it can use newer google format versions.