[codegen][java]Issue 8055: create javadoc and source jar from gradle build (#8056)

* Update build.gradle.mustache

creating javadoc and source jar fieles

* Update build.gradle.mustache

* Update build.gradle.mustache

Author: inidona

modules/swagger-codegen/src/main/resources/Java/build.gradle.mustache

@@ -18,7 +18,6 @@ repositories {
     jcenter()
 }
 
-
 if(hasProperty('target') && target == 'android') {
 
     apply plugin: 'com.android.library'
@@ -103,6 +102,21 @@ if(hasProperty('target') && target == 'android') {
        main = System.getProperty('mainClass')
        classpath = sourceSets.main.runtimeClasspath
     }
+    
+    task sourcesJar(type: Jar, dependsOn: classes) {
+        classifier = 'sources'
+        from sourceSets.main.allSource
+    }
+
+    task javadocJar(type: Jar, dependsOn: javadoc) {
+        classifier = 'javadoc'
+        from javadoc.destinationDir
+    }
+
+    artifacts {
+        archives sourcesJar
+        archives javadocJar
+    }
 }
 
 ext {
@@ -135,3 +149,4 @@ dependencies {
     {{/java8}}
     testCompile "junit:junit:$junit_version"
 }
+