question: return the data field of this event , if available . concode_field_sep T data concode_elem_sep String comment concode_elem_sep String id concode_elem_sep String event concode_elem_sep Duration retry concode_field_sep ServerSentEvent<T> build concode_elem_sep ServerSentEvent<T> build concode_elem_sep Builder<T> builder concode_elem_sep Builder<T> builder concode_elem_sep Optional<String> comment concode_elem_sep Builder<T> comment concode_elem_sep Builder<T> comment concode_elem_sep Optional<String> id concode_elem_sep Builder<T> id concode_elem_sep Builder<T> id concode_elem_sep Optional<String> event concode_elem_sep Builder<T> event concode_elem_sep Builder<T> event concode_elem_sep Optional<Duration> retry concode_elem_sep Builder<T> retry concode_elem_sep Builder<T> retry
target: Optional < T > function ( ) { return Optional . ofNullable ( this . data ) ; }