### Question:
JavaIdentifierUtils { public static boolean isJavaCoreClass(String javaClassName) { return javaClassName.startsWith("java.") || javaClassName.startsWith("javax."); }  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 isJavaCoreClass() { assertTrue(JavaIdentifierUtils.isJavaCoreClass("java.lang.Exception")); assertTrue(JavaIdentifierUtils.isJavaCoreClass("javax.lang.Exception")); assertFalse(JavaIdentifierUtils.isJavaCoreClass("org.dummy.Exception")); }