Maven shade plugin ResourceTransformer API changed

[zman0900]

Using org.springframework.boot.maven.PropertiesMergingResourceTransformer as a transformer with maven-shade-plugin is no longer possible as of shade plugin 3.2.3. The API of org.apache.maven.plugins.shade.resource.ResourceTransformer was changed, which causes an AbstractMethodError:

Execution default of goal org.apache.maven.plugins:maven-shade-plugin:3.2.3:shade failed: An API incompatibility was encountered while executing org.apache.maven.plugins:maven-shade-plugin:3.2.3:shade: java.lang.AbstractMethodError: Receiver class org.springframework.boot.maven.PropertiesMergingResourceTransformer does not define or inherit an implementation of the resolved method 'abstract void processResource(java.lang.String, java.io.InputStream, java.util.List, long)' of interface org.apache.maven.plugins.shade.resource.ResourceTransformer.

Above error is from running maven with Java 11. Running with Java 8 produces a similar, but much less useful error:

Execution default of goal org.apache.maven.plugins:maven-shade-plugin:3.2.3:shade failed: An API incompatibility was encountered while executing org.apache.maven.plugins:maven-shade-plugin:3.2.3:shade: java.lang.AbstractMethodError: null

This happens with latest spring-boot-maven-plugin 2.2.6.RELEASE.

[wilkinsona]

@zman0900 Thanks for letting us know. As things stand, anyone use Spring Boot's plugin management will be unaffected as the managed version of the Shade Plugin is 3.2.2 so hopefully the impact will be minimal at the moment.

Before we change anything in Spring Boot, I've opened MSHADE-363 to see if binary compatibility can be restored to the ResourceTransformer interface.

[wilkinsona]

3.2.4 of the Shade plugin has addressed this.