If the table you want to access is in a schema, you have to explicitly address is by prepending the schemaname. For example:
@Table(name="employee_details")
Might work better if you change it to:
@Table(name="mytestschema.employee_details")
Or, if you want the postgres user to automatically see data in non standard schemas you can modify the postgres settings to include the schema in the search path.
alter role postgres set search_path to public, mytestschema;
Once entered, every time postgres connects the tables/views/functions that are referenced will be looked for in the public schema first, then the mytestschema. Doing it this way you don't have to change the table name to include the schema first.
-g