If you are submitting a bug, please include the following:

• summary of problem

Three things:

• On Java 13, SpecificFilesTest fails with IllegalArgumentException. See logs
• The test passes with Java 8, yet, when I copy the config shown in the test verbatim I have to fix a few things for the test:
  • I have to add the version number to the plugin import to make it run at all
  • I have to add the target field to the Spotless config to make it lint any files
• The test passes with Java 8, but adding -PspotlessFiles=Test.java does not lint Test.java. See the output listed in this comment on another issue. This was attempted both on Java 8 and Java 13. Both produce the same result.

• gradle or maven version

$ gradle --version

------------------------------------------------------------
Gradle 6.2
------------------------------------------------------------

Build time:   2020-02-17 08:32:01 UTC
Revision:     61d3320259a1a0d31519bf208eb13741679a742f

Kotlin:       1.3.61
Groovy:       2.5.8
Ant:          Apache Ant(TM) version 1.10.7 compiled on September 1 2019
JVM:          13.0.1 (Oracle Corporation 13.0.1+9)
OS:           Mac OS X 10.15.3 x86_64

• spotless version
  3.27.1
• operating system and version
  MacOSX 10.15.3
• copy-paste your full Spotless configuration block(s), and a link to a public git repo that reproduces the problem if possible

buildscript { repositories { mavenCentral() } }
plugins {
    id 'com.diffplug.gradle.spotless' version "3.27.1"
}
apply plugin: 'java'
spotless {
    java {
        target '**/*.java'
        googleJavaFormat('1.2')
    }
}

• copy-paste the full content of any console errors emitted by gradlew spotless[Apply/Check] --stacktrace

No errors, which is unexpected. A lint error is expected see this comment