### Question:
CommonSchemaElements implements SchemaFileElement { @Override public final Map<String, List<String>> getExtraProperties() { return extraProperties; } protected  CommonSchemaElements(String primaryName,
      Collection<String> names, String oid, String description,
      boolean isObsolete, Map<String, List<String>> extraProperties); static void checkSafeProperties(Map <String,List<String>>
      extraProperties); final String getPrimaryName(); final Set<String> getNormalizedNames(); final Iterable<String> getUserDefinedNames(); final boolean hasName(String lowerName); final String getOID(); final String getNameOrOID(); final String getNormalizedPrimaryNameOrOID(); final boolean hasNameOrOID(String lowerValue); static String getSchemaFile(SchemaFileElement elem); static String getSingleValueProperty(SchemaFileElement elem,
      String propertyName); static void setSchemaFile(SchemaFileElement elem, String schemaFile); final String getDescription(); final boolean isObsolete(); @Override final Map<String, List<String>> getExtraProperties(); static void setExtraProperty(SchemaFileElement elem,
      String name, String value); final void setExtraProperty(String name,
                                     List<String> values); @Override final boolean equals(Object o); @Override final int hashCode(); static String getDefinitionWithFileName(SchemaFileElement elem);  }### Answer:
@Test public final void testGetExtraPropertyDefault() throws Exception { SchemaDefinitionBuilder builder = getBuilder("test", "1.2.3"); CommonSchemaElements d = builder.getInstance(); Assert.assertNull(d.getExtraProperties().get("test")); }
@Test public final void testGetExtraProperties() throws Exception { SchemaDefinitionBuilder builder = getBuilder("test", "1.2.3"); String[] expectedValues = new String[] { "one", "two" }; builder.addExtraProperty("test", expectedValues); CommonSchemaElements d = builder.getInstance(); List<String> values = d.getExtraProperties().get("test"); Assert.assertNotNull(values); for (int i = 0; i < values.size(); i++) { Assert.assertEquals(values.get(i), expectedValues[i]); } }
@Test public final void testGetExtraPropertyNames() throws Exception { SchemaDefinitionBuilder builder = getBuilder("test", "1.2.3"); CommonSchemaElements d = builder.getInstance(); Assert.assertFalse(d.getExtraProperties().keySet().iterator().hasNext()); }