Adding default User-Agent for netty and okhttp.
diff --git a/build.gradle b/build.gradle
index 968c5eb..1861a77 100644
--- a/build.gradle
+++ b/build.gradle
@@ -28,11 +28,21 @@
         mavenLocal()
     }
 
+
     [compileJava, compileTestJava].each() {
         it.options.compilerArgs += ["-Xlint:unchecked", "-Xlint:deprecation", "-Xlint:-options"]
         it.options.encoding = "UTF-8"
     }
 
+    jar.manifest {
+        attributes('Implementation-Title': name,
+                'Implementation-Version': version,
+                'Built-By': System.getProperty('user.name'),
+                'Built-JDK': System.getProperty('java.version'),
+                'Source-Compatibility': sourceCompatibility,
+                'Target-Compatibility': targetCompatibility)
+    }
+
     javadoc.options {
         encoding = 'UTF-8'
         links 'https://docs.oracle.com/javase/8/docs/api/'