### Question:
XMLSchemaCache extends SchemaCache { @Nonnull public static XMLSchemaCache getInstance () { final XMLSchemaCache ret = SingletonHolder.s_aInstance; s_bDefaultInstantiated = true; return ret; } XMLSchemaCache();  XMLSchemaCache(@Nullable final ErrorHandler aErrorHandler);  XMLSchemaCache(@Nullable final LSResourceResolver aResourceResolver);  XMLSchemaCache(@Nullable final ErrorHandler aErrorHandler, @Nullable final LSResourceResolver aResourceResolver);  XMLSchemaCache(@Nonnull final SchemaFactory aSchemaFactory,
                         @Nullable final ErrorHandler aErrorHandler,
                         @Nullable final LSResourceResolver aResourceResolver); @Nonnull static SchemaFactory createXSDSchemaFactory(); static boolean isInstantiated(); @Nonnull static XMLSchemaCache getInstance(); @Nonnull static XMLSchemaCache getInstanceOfClassLoader(@Nullable final IHasClassLoader aClassLoaderProvider); @Nonnull static XMLSchemaCache getInstanceOfClassLoader(@Nullable final ClassLoader aClassLoader); @Nonnull static EChange clearPerClassLoaderCache();  }### Answer:
@Test public void testDefault () { final XMLSchemaCache sc = XMLSchemaCache.getInstance (); assertNotNull (sc); Schema aSchema = sc.getSchema (new ClassPathResource ("xml/schema1.xsd")); assertNotNull (aSchema); assertNotNull (sc.getValidatorFromSchema (aSchema)); aSchema = sc.getSchema (new ClassPathResource ("xml/schema2.xsd")); assertNotNull (aSchema); assertNotNull (sc.getValidatorFromSchema (aSchema)); sc.clearCache (); assertFalse (sc.clearCache ().isChanged ()); aSchema = sc.getSchema (new ClassPathResource ("xml/schema1.xsd"), new ClassPathResource ("xml/schema1.xsd")); assertNotNull (aSchema); assertNotNull (sc.getValidatorFromSchema (aSchema)); aSchema = sc.getSchema (new ClassPathResource ("xml/schema1.xsd"), new ClassPathResource ("xml/schema2.xsd")); assertNotNull (aSchema); assertNotNull (sc.getValidatorFromSchema (aSchema)); final IReadableResource aPath = new ClassPathResource ("xml/schema1.xsd"); sc.removeFromCache (aPath); assertFalse (sc.removeFromCache (aPath).isChanged ()); try { sc.getSchema (new ClassPathResource ("test1.txt")); fail (); } catch (final IllegalArgumentException ex) {} try { sc.getSchema ((IReadableResource) null); fail (); } catch (final NullPointerException ex) {} }