Developer Guide

Building with Java 21 and Java 11 compatibility

The build uses Java 21 as its primary JDK. Maven selects that JDK through the java.version property in pom.xml and the Maven Toolchains configuration.

Run the complete build, including integration tests, with:

mvn clean verify

The published library remains compatible with Java 11. The Maven Compiler and Javadoc plugins use --release 11 (<release>11</release>), which both emits Java 11 bytecode and limits the available Java APIs to the Java 11 API surface.

Consequently, production code must not use Java language features or JDK APIs introduced after Java 11, even though the build runs on Java 21.

The CI build also runs the regular unit-test selection with Java 11 to validate that compatibility:

mvn --batch-mode clean test \
    -Djava.version=11 \
    -Denforcer.skip=true

-Denforcer.skip=true is required because the normal build requires Java 21.

The test goal runs Maven Surefire only; use verify on Java 21 to include the Maven Failsafe integration tests.

For Java 11 we only run unit tests in CI, since the integration test require Apache Derby and up-to-date versions of Derby only run with Java 21.