added comments and tests.

opp/core/src/main/java/OPStaff.java

opp/core/src/main/java/OPStaffService.java

opp/core/src/main/java/OPStaffServiceImpl.java

opp/core/src/main/java/Operation.java

opp/core/src/main/java/OperationService.java

opp/core/src/main/java/OperationServiceImpl.java

opp/core/src/main/java/OperationTeam.java

opp/core/src/main/java/OperationTeamService.java

opp/core/src/main/java/OperationTeamServiceImpl.java

opp/core/src/main/java/Patient.java

opp/core/src/main/java/PreparationNote.java

opp/core/src/main/java/PreparationNoteService.java

opp/core/src/main/java/PreparationNoteServiceImpl.java

opp/core/src/main/java/Role.java

opp/core/src/main/java/Room.java

opp/core/src/main/java/RoomService.java

opp/core/src/main/java/RoomServiceImpl.java

opp/core/src/main/java/Specialty.java

opp/jdbc-repo-impl/src/main/java/JDBCRepository.java

opp/jdbc-repo-impl/src/test/java/Tests.java