Generate a test dependencies file to support unit tests in entitlements (#127486) (#128280)

Generates a test file with the following information and format:

{
    "component": "<component name>",
    "locations": [
        {
            "representative_class": <class name with package>,
            "module": "<module name>"
        },
        ...
    ]
}

For painless:

{
    "component": "lang-painless",
    "locations": [
        {
            "representative_class": "org/objectweb/asm/tree/analysis/Analyzer.class",
            "module": "org.objectweb.asm.tree.analysis"
        },
        ...
    ]
}

Then it copies the following files into the jar for consumption by unit tests:

* META-INF/plugin-test-build-info.json
* META-INF/es-plugins/<plugin name>/plugin-descriptor.properties
* META-INF/es-plugins/<plugin name>/entitlement-policy.yaml

For server, the files in the jar become the following:

* META-INF/server-test-build-info.json

This should provide enough information for BootstrapForTesting to be 
able to build a mapping of caller class to policy file using the class file 
to look up the jar or directory within the class path and then associating 
that with it's specified module and finally using the specified module to 
look up the appropriate entitlement policy. 

caller class -> specified module -> entitlement policy


---------

Co-authored-by: Patrick Doyle <[email protected]>

Author: jdconrad

build-tools/build.gradle

@@ -51,6 +51,10 @@ gradlePlugin {
           id = 'elasticsearch.stable-esplugin'
           implementationClass = 'org.elasticsearch.gradle.plugin.StablePluginBuildPlugin'
         }
+        testBuildInfo {
+          id = 'elasticsearch.test-build-info'
+          implementationClass = 'org.elasticsearch.gradle.test.TestBuildInfoPlugin'
+        }
         javaRestTest {
             id = 'elasticsearch.java-rest-test'
             implementationClass = 'org.elasticsearch.gradle.test.JavaRestTestPlugin'

build-tools/src/integTest/groovy/org/elasticsearch/gradle/test/TestBuildInfoPluginFuncTest.groovy

@@ -0,0 +1,63 @@
+package org.elasticsearch.gradle.test
+
+import com.fasterxml.jackson.databind.ObjectMapper
+
+import org.elasticsearch.gradle.fixtures.AbstractGradleFuncTest
+import org.gradle.testkit.runner.TaskOutcome
+
+class TestBuildInfoPluginFuncTest extends AbstractGradleFuncTest {
+    def "works"() {
+        given:
+        file("src/main/java/com/example/Example.java") << """
+            package com.example;
+
+            public class Example {
+            }
+        """
+
+        file("src/main/java/module-info.java") << """
+            module com.example {
+                exports com.example;
+            }
+        """
+
+        buildFile << """
+        import org.elasticsearch.gradle.plugin.GenerateTestBuildInfoTask;
+
+        plugins {
+            id 'java'
+            id 'elasticsearch.test-build-info'
+        }
+
+        repositories {
+            mavenCentral()
+        }
+
+        tasks.withType(GenerateTestBuildInfoTask.class) {
+            componentName = 'example-component'
+            outputFile = new File('build/generated-build-info/plugin-test-build-info.json')
+        }
+        """
+
+        when:
+        def result = gradleRunner('generateTestBuildInfo').build()
+        def task = result.task(":generateTestBuildInfo")
+
+
+        then:
+        task.outcome == TaskOutcome.SUCCESS
+
+        def output = file("build/generated-build-info/plugin-test-build-info.json")
+        output.exists() == true
+
+        def location = Map.of(
+            "module", "com.example",
+            "representative_class", "com/example/Example.class"
+        )
+        def expectedOutput = Map.of(
+            "component", "example-component",
+            "locations", List.of(location)
+        )
+        new ObjectMapper().readValue(output, Map.class) == expectedOutput
+    }
+}

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

@@ -121,7 +121,10 @@ private TaskProvider<Zip> createBundleTasks(final Project project, PluginPropert
             task.getIsLicensed().set(providerFactory.provider(extension::isLicensed));
 
             var mainSourceSet = project.getExtensions().getByType(SourceSetContainer.class).getByName(SourceSet.MAIN_SOURCE_SET_NAME);
-            FileCollection moduleInfoFile = mainSourceSet.getOutput().getAsFileTree().matching(p -> p.include("module-info.class"));
+            FileCollection moduleInfoFile = mainSourceSet.getOutput()
+                .getClassesDirs()
+                .getAsFileTree()
+                .matching(p -> p.include("module-info.class"));
             task.getModuleInfoFile().setFrom(moduleInfoFile);
 
         });