### Question:
MetadataUtils { public static Set<String> deserializeKeys(String foreignKeys) { Set<String> keys = new HashSet<String>(); if (null == foreignKeys || foreignKeys.isEmpty()) { return keys; } String array[] = foreignKeys.split(Constants.FOREIGN_KEY_SEPARATOR); for (String element : array) { keys.add(element); } return keys; }  static void populateColumnAndSuperColumnMaps(EntityMetadata m, Map<String, Field> columnNameToFieldMap,
            Map<String, Field> superColumnNameToFieldMap, final KunderaMetadata kunderaMetadata); static Map<String, Field> createColumnsFieldMap(EntityMetadata m, EmbeddableType superColumn); static Map<String, Field> createSuperColumnsFieldMap(final EntityMetadata m,
            final KunderaMetadata kunderaMetadata); static Collection getEmbeddedCollectionInstance(Field embeddedCollectionField); static Object getEmbeddedGenericObjectInstance(Field embeddedCollectionField); static String getEmbeddedCollectionPrefix(String embeddedCollectionName); static String getEmbeddedCollectionPostfix(String embeddedCollectionName); static String serializeKeys(Set<String> foreignKeys); static Set<String> deserializeKeys(String foreignKeys); static void setSchemaAndPersistenceUnit(EntityMetadata m, String schemaStr, Map puProperties); static boolean useSecondryIndex(ClientMetadata clientMetadata); static String getMappedName(EntityMetadata parentMetadata, Relation relation,
            final KunderaMetadata kunderaMetadata); static String getEnclosingEmbeddedFieldName(EntityMetadata m, String criteria, boolean viaColumnName,
            final KunderaMetadata kunderaMetadata); static boolean isEmbeddedAtributeIndexable(Field embeddedField); static boolean isColumnInEmbeddableIndexable(Field embeddedField, String columnFieldName); static boolean defaultTransactionSupported(final String persistenceUnit,
            final KunderaMetadata kunderaMetadata); static boolean isSchemaAttributeRequired(final String persistenceUnit, final KunderaMetadata kunderaMetadata); static boolean indexSearchEnabled(final String persistenceUnit, final KunderaMetadata kunderaMetadata); static boolean isBasicElementCollectionField(Field collectionField); static boolean containsBasicElementCollectionField(final EntityMetadata m,
            final KunderaMetadata kunderaMetadata); static void onJPAColumnMapping(final EntityType entityType, EntityMetadata entityMetadata); static boolean onCheckValidationConstraints(Field attribute); static boolean onCheckEmbeddableAttribute(Field attribute);  }### Answer:
@Test public void testDeserializeKeys() { final String serializedKey = "key1~key2~key3"; Set<String> foreignKeys = MetadataUtils.deserializeKeys(serializedKey); Assert.assertNotNull(foreignKeys); Assert.assertEquals(3, foreignKeys.size()); }