void addSourceRoot(File outputDir) {
		if (generateTestSources) {
			project.addTestCompileSourceRoot(outputDir.getPath());
		}
		else {
			project.addCompileSourceRoot(outputDir.getPath());
		}
    }
The directory where build status information is located.
antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/Antlr4Mojo.java