protect task for plugins with no source

Author: jdconrad

build-tools/src/main/java/org/elasticsearch/gradle/plugin/GenerateTestBuildInfoTask.java

@@ -184,16 +184,18 @@ public ModuleVisitor visitModule(String name, int access, String version) {
             writer.write("\",\n");
 
             writer.write("    \"locations\": [\n");
-            StringBuilder sb = new StringBuilder();
-            for (Map.Entry<String, String> entry : classesToModules.entrySet()) {
-                sb.append("        {\n");
-                sb.append("            \"class\": \"");
-                sb.append(entry.getKey());
-                sb.append("\",\n            \"module\": \"");
-                sb.append(entry.getValue());
-                sb.append("\"\n        },\n");
+            if (classesToModules.isEmpty() == false) {
+                StringBuilder sb = new StringBuilder();
+                for (Map.Entry<String, String> entry : classesToModules.entrySet()) {
+                    sb.append("        {\n");
+                    sb.append("            \"class\": \"");
+                    sb.append(entry.getKey());
+                    sb.append("\",\n            \"module\": \"");
+                    sb.append(entry.getValue());
+                    sb.append("\"\n        },\n");
+                }
+                writer.write(sb.substring(0, sb.length() - 2));
             }
-            writer.write(sb.substring(0, sb.length() - 2));
             writer.write("\n    ]\n}\n");
         }
     }

build-tools/src/main/java/org/elasticsearch/gradle/plugin/PluginBuildPlugin.java

@@ -82,5 +82,4 @@ public void apply(final Project project) {
             task.into("META-INF", copy -> copy.from(testBuildInfoTask));
         });
     }
-
 }

build-tools/src/main/java/org/elasticsearch/gradle/test/TestBuildInfoPlugin.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+package org.elasticsearch.gradle.test;
+
+import org.gradle.api.Plugin;
+import org.gradle.api.Project;
+
+public class TestBuildInfoPlugin implements Plugin<Project> {
+
+    @Override
+    public void apply(Project project) {
+
+    }
+}

server/build.gradle

@@ -11,6 +11,7 @@ apply plugin: 'elasticsearch.build'
 apply plugin: 'elasticsearch.publish'
 apply plugin: 'elasticsearch.internal-cluster-test'
 apply plugin: 'elasticsearch.internal-test-artifact'
+// TODO: apply new plugin
 
 publishing {
   publications {
@@ -284,3 +285,5 @@ tasks.named("licenseHeaders").configure {
 }
 
 tasks.withType(Checkstyle.class).configureEach { t -> t.getMaxHeapSize().set("2g") }
+
+// TODO: add tasks.named for new task and set server as component