OZG-6990 implement comments from code review

...oud/apilib/client_attribute/OzgCloudAccessPermission.java

...ilib/client_attribute/OzgCloudBooleanClientAttribute.java

...loud/apilib/client_attribute/OzgCloudClientAttribute.java

...ilib/client_attribute/OzgCloudClientAttributeService.java

...pilib/client_attribute/OzgCloudDoubleClientAttribute.java

.../apilib/client_attribute/OzgCloudLongClientAttribute.java

...pilib/client_attribute/OzgCloudStringClientAttribute.java

...nt_attribute/grpc/OzgCloudClientAttributeGrpcService.java

.../client_attribute/grpc/OzgCloudClientAttributeMapper.java

...ilib/client_attribute/GrpcClientAttributeTestFactory.java

.../client_attribute/OzgCloudClientAttributeTestFactory.java

...ttribute/grpc/OzgCloudClientAttributeGrpcServiceTest.java

...ent_attribute/grpc/OzgCloudClientAttributeMapperTest.java