Simplify java home verification

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -182,60 +182,6 @@ class BuildPlugin implements Plugin<Project> {
         }
     }
 
-    /** Add a check before gradle execution phase which ensures java home for the given java version is set. */
-    static void requireJavaHome(Task task, int version) {
-        // use root project for global accounting
-        Project rootProject = task.project.rootProject
-        ExtraPropertiesExtension extraProperties = rootProject.extensions.extraProperties
-
-        // hacky way (but the only way) to find if the task graph has already been populated
-        boolean taskGraphReady
-        try {
-            rootProject.gradle.taskGraph.getAllTasks()
-            taskGraphReady = true
-        } catch (IllegalStateException) {
-            taskGraphReady = false
-        }
-
-        if (taskGraphReady) {
-            // check directly if the version is present since we are already executing
-            if (BuildParams.javaVersions.find { it.version == version } == null) {
-                throw new GradleException("JAVA${version}_HOME required to run task:\n${task}")
-            }
-        } else {
-            // setup list of java versions we will check at the end of configuration time
-            if (extraProperties.has('requiredJavaVersions') == false) {
-                extraProperties.set('requiredJavaVersions', [:])
-                rootProject.gradle.taskGraph.whenReady { TaskExecutionGraph taskGraph ->
-                    List<String> messages = []
-                    Map<Integer, List<Task>> requiredJavaVersions = (Map<Integer, List<Task>>) extraProperties.get('requiredJavaVersions')
-                    for (Map.Entry<Integer, List<Task>> entry : requiredJavaVersions) {
-                        if (BuildParams.javaVersions.any { it.version == entry.key }) {
-                            continue
-                        }
-                        List<String> tasks = entry.value.findAll { taskGraph.hasTask(it) }.collect { "  ${it.path}".toString() }
-                        if (tasks.isEmpty() == false) {
-                            messages.add("JAVA${entry.key}_HOME required to run tasks:\n${tasks.join('\n')}".toString())
-                        }
-                    }
-                    if (messages.isEmpty() == false) {
-                        throw new GradleException(messages.join('\n'))
-                    }
-                }
-            }
-            Map<Integer, List<Task>> requiredJavaVersions = (Map<Integer, List<Task>>) extraProperties.get('requiredJavaVersions')
-            requiredJavaVersions.putIfAbsent(version, [])
-            requiredJavaVersions.get(version).add(task)
-        }
-    }
-
-    /** A convenience method for getting java home for a version of java and requiring that version for the given task to execute */
-    static String getJavaHome(final Task task, final int version) {
-        requireJavaHome(task, version)
-        JavaHome java = BuildParams.javaVersions.find { it.version == version }
-        return java == null ? null : java.javaHome.get().absolutePath
-    }
-
     /**
      * Makes dependencies non-transitive.
      *

buildSrc/src/main/java/org/elasticsearch/gradle/util/JavaUtil.java

@@ -0,0 +1,42 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you 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.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.gradle.util;
+
+import org.elasticsearch.gradle.info.BuildParams;
+import org.elasticsearch.gradle.info.JavaHome;
+import org.gradle.api.GradleException;
+import org.gradle.api.Task;
+
+import java.util.List;
+import java.util.Optional;
+
+public class JavaUtil {
+
+    /** A convenience method for getting java home for a version of java and requiring that version for the given task to execute */
+    static String getJavaHome(final Task task, final int version) {
+        List<JavaHome> javaHomes = BuildParams.getJavaVersions();
+        Optional<JavaHome> java = javaHomes.stream().filter(j -> j.getVersion() == version).findFirst();
+        // check directly if the version is present since we are already executing
+        if (java.isEmpty()) {
+            throw new GradleException("JAVA" + version + "_HOME required to run task " + task.getPath());
+        }
+        return java.get().getJavaHome().get().getAbsolutePath();
+    }
+}

distribution/bwc/build.gradle

@@ -27,7 +27,7 @@ import org.gradle.util.GradleVersion
 
 import java.nio.charset.StandardCharsets
 
-import static org.elasticsearch.gradle.BuildPlugin.getJavaHome
+import static org.elasticsearch.gradle.util.JavaUtil.getJavaHome
 
 /**
  *  We want to be able to do BWC tests for unreleased versions without relying on and waiting for snapshots.

modules/reindex/build.gradle

@@ -22,8 +22,6 @@ import org.elasticsearch.gradle.Architecture
 import org.elasticsearch.gradle.OS
 import org.elasticsearch.gradle.info.BuildParams
 
-import static org.elasticsearch.gradle.BuildPlugin.getJavaHome
-
 apply plugin: 'elasticsearch.test-with-dependencies'
 apply plugin: 'elasticsearch.jdk-download'