### Question:
JavaIdentifierUtils { public static boolean isInnerClass(String javaClassName) { return javaClassName.contains("$") && !javaClassName.endsWith("$"); }  static String getJavaClassSimpleName(String javaClassName); static boolean isInnerClass(String javaClassName); static boolean isValidClassName(String className); static int getJavaClassNestingLevel(String javaClassName); static boolean isValidConstantName(String fieldName); static String getPackageName(String javaClassName); static boolean isJavaCoreClass(String javaClassName); static boolean hasSuperclassOrImplementsInterface(Class<?> javaClass, String superJavaClassOrInterfaceName); static Set<String> removeInnerClassesAndInvalidClassNames(Set<String> javaClassNames); static Set<String> javaClassNamesToPackages(Set<String> javaClassNames); static Set<String> removeJavaCoreClassNames(Set<String> javaClassNames);  }### Answer:
@Test public void isInnerClass() { assertTrue(JavaIdentifierUtils.isInnerClass("Bla$Test")); assertTrue(JavaIdentifierUtils.isInnerClass("dummy.Bla$Test$Blub")); assertFalse(JavaIdentifierUtils.isInnerClass("test.$")); }