GP-5257: Fixing Gradle warnings

gradle/hasProtobuf.gradle

@@ -4,9 +4,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -73,10 +73,10 @@ task generateProto {
 		if (!isCurrentWindows()) {
 			exe.setExecutable(true)
 		}
-		exec {
+		providers.exec {
 			commandLine exe, "--java_out=$outdir", "-I$srcdir"
 			args src
-		}
+		}.result.get()
 	}
 }