### Question:
Configuration { public boolean isImmutable(String className) { return immutableClasses.contains(className); } private  Configuration(); static Configuration instance(); Set<String> getImmutableClasses(); Set<String> getSafeClasses(); boolean isImmutable(String className); boolean isMutable(String className); boolean isSafe(String typeSignature); boolean isUnsafeMethod(String methodDescriptor); static final String IMMUTABLE_CLASSES_PATH; static final String SAFE_CLASSES_PATH; static final String SAFE_METHODS_PATH; static final String UNSAFE_METHODS_PATH; static final String FRAMEWORK_CLASSES_PATH; static final String SAFE_FRAMEWORK_CLASSES_PATH; }### Answer:
@Test public void stringIsImmutable() { assertTrue(configuration.isImmutable("Ljava/lang/String;")); }
@Test public void stringArrayIsImmutable() { assertFalse(configuration.isImmutable("[Ljava/lang/String;")); }
@Test public void stringBuilderIsImmutable() { assertFalse(configuration.isImmutable("Ljava/lang/StringBuilder;")); }