Remove unused task

runners/google-cloud-dataflow-java/worker/build.gradle

@@ -194,8 +194,6 @@ dependencies {
 
   runtime library.java.slf4j_jdk14
 
-  sourceFile "javax.servlet:javax.servlet-api:3.1.0:sources"
-
   testCompile "org.apache.beam:beam-runners-core-java:$version:tests"
   testCompile "org.apache.beam:beam-runners-direct-java:$version"
   testCompile "org.apache.beam:beam-sdks-java-core:$version:tests"
@@ -208,20 +206,6 @@ dependencies {
   testCompile library.java.mockito_core
 }
 
-/******************************************************************************/
-// Extract required source files under '$buildDir/original_sources_to_package',
-// which will be packed into jar file.
-
-task extractSourceFiles(type: Copy) {
-  configurations.sourceFile.files.each {
-    if (it.name.contains("javax.servlet-api")) {
-      from zipTree(it)
-      into "$buildDir/original_sources_to_package/sources/javax.servlet-api"
-    }
-  }
-}
-shadowJar.dependsOn extractSourceFiles
-
 //TODO(BEAM-5657): checktyle task should be enabled in the future.
 checkstyleMain.enabled = false
 checkstyleTest.enabled = false