Cleanup implementation of REST views

- specify return type if possible
- remove unnecessary throw declarations
- convert some of the thrown exceptions to RestExceptions
- do not throw Exception but specific exceptions
- sort throw declarations (first RestExceptions, then other
  exceptions)

Having explicit return types and exceptions makes it easier to
programatically invoke the REST views, e.g. if a plugin wants to add a
REST view that wraps a Gerrit core REST view.

Change-Id: I5c59553b6cfad457f7ec037cceb08936247bf8e8
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

gerrit-server/src/main/java/com/google/gerrit/server/change/PostReviewers.java

@@ -28,7 +28,6 @@ import com.google.gerrit.common.errors.NoSuchGroupException;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.DefaultInput;
-import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.RestModifyView;
 import com.google.gerrit.extensions.restapi.UnprocessableEntityException;
 import com.google.gerrit.reviewdb.client.Account;
@@ -132,8 +131,8 @@ public class PostReviewers implements RestModifyView<ChangeResource, Input> {
 
   @Override
   public PostResult apply(ChangeResource rsrc, Input input)
-      throws BadRequestException, ResourceNotFoundException, AuthException,
-      UnprocessableEntityException, OrmException, EmailException, IOException {
+      throws AuthException, BadRequestException, UnprocessableEntityException,
+      OrmException, EmailException, IOException {
     if (input.reviewer == null) {
       throw new BadRequestException("missing reviewer field");
     }