annotations - an array of the annotations on the declaration of the artifact that will be written. E.g. if the message body is to be produced from a field, this will be the annotations on that field returned by Field.getDeclaredAnnotations.
Obviously, Field.getDeclaredAnnotations can be null.
But, as Jersey contains EntityMessageWriter provider, which tries to get path value, and AbstractMessageBodyRW does not check for null annotations, this throws NPE.