Returns the values of this annotation's elements.
This is returned in the form of a map that associates elements
with their corresponding values.
Only those elements with values explicitly present in the
annotation are included, not those that are implicitly assuming
their default values.
The order of the map matches the order in which the
values appear in the annotation's source.
Note that an annotation mirror of a marker annotation type
will by definition have an empty map.
To fill in default values, use {@link
javax.lang.model.util.Elements#getElementValuesWithDefaults
getElementValuesWithDefaults}.
