REST services are validated based on the REST annotations present at the class, method, and method parameters level. The validation is done in the REST annotation processor.
Tto see the validation messages on a REST service, turn on annotation processing at the project level, through the project properties dialog. By default, annotation processing on a project is not enabled.
There is a quick fix bulb icon on the validation output window which you can select to resolve the following :
Issues with the values in the PathParam annotation.
Issues related to converting a non-public resource method to a public method.
To show annotation validations:
Go to File > Properties.
Select Java Compiler > Annotation Processing.
Select Enable project specific settings, and Enable annotation processing.