    @Test
    @SuppressWarnings("PMD.AvoidDuplicateLiterals")
    public void doesNotComplainAboutConstantsInInnerClasses() throws Exception {

        final String file = "src/main/java/foo/Foo.java";
        final Environment env = new Environment.Mock().withFile(
            file,
            Joiner.on('\n').join(
                "package foo;",
                "interface Foo {",
                "  final class Bar implements Foo {",
                "    private static final Pattern TEST =",
                "      Pattern.compile(\"hey\");",
                "    public String doSomething() {",
                "      return Foo.Bar.TEST.toString();",
                "    }",
                "  }",
                "}"
            )
        );
        MatcherAssert.assertThat(
            new PmdValidator(env).validate(
                Collections.singletonList(new File(env.basedir(), file))
            ),
            Matchers.<Violation>empty()
        );
    }