### Question:
GenericCollectionTypeResolver { public static Class<?> getMapKeyFieldType(Field mapField) { return getGenericFieldType(mapField, Map.class, 0, getNestingLevel(mapField.getGenericType(), 0)); }  static Class<?> getCollectionFieldType(Field collectionField); static Class<?> getMapKeyFieldType(Field mapField); static Class<?> getMapValueFieldType(Field mapField); static Class<?> getCollectionParameterType(MethodParameter methodParam); static Class<?> getMapKeyParameterType(MethodParameter methodParam); static Class<?> getMapValueParameterType(MethodParameter methodParam);  }### Answer:
@Test public void testGetMapKeyFieldType() throws Exception { final Class<?> mapKeyFieldType = GenericCollectionTypeResolver.getMapKeyFieldType(getMapField()); assertEquals(String.class, mapKeyFieldType); }