如何调试第三方Gradle插件？

我正在尝试使用gradle签名插件签署 Android AAR工件.不幸的是,我NullPointerException在这个过程中得到了一个相当无助的东西:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':library:signArchives'.
> java.lang.NullPointerException (no error message)

* Try:
Run with --info or --debug option to get more log output.

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':library:signArchives'.
        at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:69)
        [...snip...]
        at org.gradle.launcher.Main.main(Main.java:37)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:50)
        at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:32)
        at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
        at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:33)
        at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:130)
        at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:48)
Caused by: java.lang.NullPointerException
        at org.bouncycastle.openpgp.PGPSignatureGenerator.initSign(Unknown Source)
        at org.bouncycastle.openpgp.PGPSignatureGenerator.initSign(Unknown Source)
        at org.bouncycastle.openpgp.PGPSignatureGenerator$initSign.call(Unknown Source)
        at org.gradle.plugins.signing.signatory.pgp.PgpSignatory.createSignatureGenerator(PgpSignatory.groovy:54)
        at org.gradle.plugins.signing.signatory.pgp.PgpSignatory.sign(PgpSignatory.groovy:64)
        [...snip...]
        ... 52 more


BUILD FAILED

调试此异常的最简单方法是什么？有没有办法将调试器附加到gradle？我可以构建签名插件,插入一些日志记录语句并告诉我的构建版本来获取我的自定义版本而不是它附带的版本吗？