LUCENE-10255: re-add utilities for debugging packages and services. These are not included by default to avoid unnecessary compilation overhead.

gradle/java/modules-debugging.gradle

@@ -0,0 +1,84 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.
+ */
+
+// Debugging/ validation utilities and helpers to aid transition
+// to java modules.
+
+allprojects {
+  plugins.withType(JavaPlugin) {
+    // Show all non-empty package names
+    tasks.register("showPackageNames", { task ->
+      doFirst {
+        listPackageNames(sourceSets).each { println(it) }
+      }
+    })
+
+    tasks.register("showServiceProviders", { task ->
+      doFirst {
+        def services = listServices(sourceSets)
+        services.each { entry -> {
+          println(entry.key)
+          entry.value.each { println("  ${it}") }
+        }}
+      }
+    })
+  }
+}
+
+/* Utility method to collect all package names in a source sets. */
+static def listPackageNames(SourceSetContainer sourceSets) {
+  var pkgNameSet = [] as Set<String>
+  sourceSets.main.each { sourceSet ->
+    var dirs = sourceSet.allJava.srcDirTrees.collect { it.dir.toPath() }
+    var pattern = new PatternSet()
+        .include('**/*.java')
+        .exclude('module-info.java')
+        .exclude('**/package-info.java')
+    sourceSet.allJava.matching(pattern).each {srcFile ->
+      var srcPath = srcFile.toPath()
+      var dir = dirs.find { srcPath.startsWith(it) }
+      var pkgName = srcPath.subpath(dir.nameCount, srcPath.nameCount).parent.stream().map(Object::toString).collect(Collectors.joining('.'))
+      pkgNameSet.add(pkgName)
+    }
+  }
+  var pkgNames = pkgNameSet as List<String>
+  pkgNames.sort()
+  return pkgNames
+}
+
+/* Utility method to collect all service providers in a source sets. */
+static def listServices(SourceSetContainer sourceSets) {
+  def services = [:] as Map<String, List<String>>
+  sourceSets.main.each {sourceSet ->
+    var pattern = new PatternSet().include('META-INF/services/*')
+    sourceSet.resources.matching(pattern).each {file ->
+      def serviceName = file.name
+      def providers = []
+      file.withReader { reader -> {
+        reader.lines().each { l ->
+          def line = l.trim()
+          if (line != "" && !line.startsWith("#")) {
+            def provider = line.replace('$', '.')
+            providers.add(provider)
+          }
+        }
+      }}
+      services.put(serviceName, providers)
+    }
+  }
+  return services
+}