The PMD plugin ignores its documented behaviour to continue the build if "project.pmd.ignoreFailures" is set to true.

The following configuration should work (=continue the build on PMD check failures) according to the docs:

apply plugin: 'pmd'

pmd {
    ignoreFailures = true
}

With this configuration pmdMain stops the build on errors.
The following snippet achieves the documented behaviour:

[pmdMain,pmdTest]*.ignoreFailures = project.pmd.ignoreFailures

The plugin should behave as documented, so IMHO it is a bug.