QueryChanges: Include exception cause in BadRequestException

Change-Id: Ibde8720fe22df5213e4b22481f80085e908e6a46

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/restapi/BadRequestException.java

@@ -22,4 +22,12 @@ public class BadRequestException extends RestApiException {
   public BadRequestException(String msg) {
     super(msg);
   }
+
+  /**
+   * @param msg error text for client describing how request is bad.
+   * @param cause cause of this exception.
+   */
+  public BadRequestException(String msg, Throwable cause) {
+    super(msg, cause);
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/query/change/QueryChanges.java

@@ -103,7 +103,7 @@ public class QueryChanges implements RestReadView<TopLevelResource> {
         String op = m.group(1);
         throw new AuthException("Must be signed-in to use " + op);
       }
-      throw new BadRequestException(e.getMessage());
+      throw new BadRequestException(e.getMessage(), e);
     }
     return out.size() == 1 ? out.get(0) : out;
   }