GRPC support for MultiJoin, improved GRPC support for RangeJoin (deep…

…haven#5153)

* MultiJoin GRPC implementation and RangeJoin GRPC update.

* Additional verification for MultiJoinRequest

* Updated the documentation.

* OperatorHelper updated.

* PR comments addressed.

* Simplified MultiJoin GRPC structures.

* Re-gen'd proto output.

* Removed incorrect comment.

* Added comments to MultiJoinInput structures.

authorization/src/main/java/io/deephaven/auth/codegen/impl/TableServiceContextualAuthWiring.java

@@ -31,6 +31,7 @@
 import io.deephaven.proto.backplane.grpc.LeftJoinTablesRequest;
 import io.deephaven.proto.backplane.grpc.MergeTablesRequest;
 import io.deephaven.proto.backplane.grpc.MetaTableRequest;
+import io.deephaven.proto.backplane.grpc.MultiJoinTablesRequest;
 import io.deephaven.proto.backplane.grpc.NaturalJoinTablesRequest;
 import io.deephaven.proto.backplane.grpc.RangeJoinTablesRequest;
 import io.deephaven.proto.backplane.grpc.RunChartDownsampleRequest;
@@ -372,6 +373,17 @@ void checkPermissionAjTables(AuthContext authContext, AjRajTablesRequest request
     void checkPermissionRajTables(AuthContext authContext, AjRajTablesRequest request,
             List<Table> sourceTables);
 
+    /**
+     * Authorize a request to MultiJoinTables.
+     *
+     * @param authContext the authentication context of the request
+     * @param request the request to authorize
+     * @param sourceTables the operation's source tables
+     * @throws io.grpc.StatusRuntimeException if the user is not authorized to invoke MultiJoinTables
+     */
+    void checkPermissionMultiJoinTables(AuthContext authContext, MultiJoinTablesRequest request,
+            List<Table> sourceTables);
+
     /**
      * Authorize a request to RangeJoinTables.
      *
@@ -677,6 +689,11 @@ public void checkPermissionRajTables(AuthContext authContext, AjRajTablesRequest
             checkPermission(authContext, sourceTables);
         }
 
+        public void checkPermissionMultiJoinTables(AuthContext authContext,
+                MultiJoinTablesRequest request, List<Table> sourceTables) {
+            checkPermission(authContext, sourceTables);
+        }
+
         public void checkPermissionRangeJoinTables(AuthContext authContext,
                 RangeJoinTablesRequest request, List<Table> sourceTables) {
             checkPermission(authContext, sourceTables);
@@ -972,6 +989,13 @@ public void checkPermissionRajTables(AuthContext authContext, AjRajTablesRequest
             }
         }
 
+        public void checkPermissionMultiJoinTables(AuthContext authContext,
+                MultiJoinTablesRequest request, List<Table> sourceTables) {
+            if (delegate != null) {
+                delegate.checkPermissionMultiJoinTables(authContext, request, sourceTables);
+            }
+        }
+
         public void checkPermissionRangeJoinTables(AuthContext authContext,
                 RangeJoinTablesRequest request, List<Table> sourceTables) {
             if (delegate != null) {