Gradle-apt-plugin re-generates all apt-generated files if one changes

Hello,

we are using the tboyer/gradle-apt-plugin 0.9 on a large amount of annotated classes.
We noticed that the annotation processing takes a serious amount of the compilation time
Even if only one of the annotated files is changed the apt-plugin seems to process all annotated files again.
Which in turn causes re-compilation of depending files.
In summary, the build time is much longer than in an previously used Ant-script, which is not smart enough to detect whether a source file has changed or not.

Running the build with --debug prints:

18:50:57.448 [INFO] [org.gradle.api.internal.changedetection.changes.RebuildIncrementalTaskInputs] All input files are considered out-of-date for incremental task ‘:myProject:compileJava’.

Does anyone has suggestions how to avoid or further analyze this problem?

Thank you in advance