[7.x] Introduce changes related to yamlRestCompatTest (#62985) (#63105)

Backport for #62985 that includes the related changes, but 
not the actual plugin for yamlRestCompatTest. The plugin 
is not necessary in 7.x, and back porting relevant changes to
help keep 7.x code inline with master.

Author: jakelandis

buildSrc/src/main/java/org/elasticsearch/gradle/test/rest/CopyRestApiTask.java

@@ -58,8 +58,10 @@ public class CopyRestApiTask extends DefaultTask {
     final ListProperty<String> includeCore = getProject().getObjects().listProperty(String.class);
     final ListProperty<String> includeXpack = getProject().getObjects().listProperty(String.class);
     String sourceSetName;
+    boolean skipHasRestTestCheck;
     Configuration coreConfig;
     Configuration xpackConfig;
+    Configuration additionalConfig;
 
     private final PatternFilterable corePatternSet;
     private final PatternFilterable xpackPatternSet;
@@ -89,6 +91,11 @@ String getSourceSetName() {
         return sourceSetName;
     }
 
+    @Input
+    public boolean isSkipHasRestTestCheck() {
+        return skipHasRestTestCheck;
+    }
+
     @SkipWhenEmpty
     @InputFiles
     public FileTree getInputDir() {
@@ -98,7 +105,7 @@ public FileTree getInputDir() {
             xpackPatternSet.setIncludes(includeXpack.get().stream().map(prefix -> prefix + "*/**").collect(Collectors.toList()));
             xpackFileTree = xpackConfig.getAsFileTree().matching(xpackPatternSet);
         }
-        boolean projectHasYamlRestTests = projectHasYamlRestTests();
+        boolean projectHasYamlRestTests = skipHasRestTestCheck || projectHasYamlRestTests();
         if (includeCore.get().isEmpty() == false || projectHasYamlRestTests) {
             if (BuildParams.isInternal()) {
                 corePatternSet.setIncludes(includeCore.get().stream().map(prefix -> prefix + "*/**").collect(Collectors.toList()));
@@ -107,7 +114,10 @@ public FileTree getInputDir() {
                 coreFileTree = coreConfig.getAsFileTree(); // jar file
             }
         }
-        ConfigurableFileCollection fileCollection = getProject().files(coreFileTree, xpackFileTree);
+
+        ConfigurableFileCollection fileCollection = additionalConfig == null
+            ? getProject().files(coreFileTree, xpackFileTree)
+            : getProject().files(coreFileTree, xpackFileTree, additionalConfig.getAsFileTree());
 
         // if project has rest tests or the includes are explicitly configured execute the task, else NO-SOURCE due to the null input
         return projectHasYamlRestTests || includeCore.get().isEmpty() == false || includeXpack.get().isEmpty() == false
@@ -132,7 +142,7 @@ void copy() {
         if (BuildParams.isInternal()) {
             getLogger().debug("Rest specs for project [{}] will be copied to the test resources.", project.getPath());
             project.copy(c -> {
-                c.from(coreConfig.getSingleFile());
+                c.from(coreConfig.getAsFileTree());
                 c.into(getOutputDir());
                 c.include(corePatternSet.getIncludes());
             });
@@ -164,6 +174,14 @@ void copy() {
                 c.include(xpackPatternSet.getIncludes());
             });
         }
+        // TODO: once https://github.com/elastic/elasticsearch/pull/62968 lands ensure that this uses `getFileSystemOperations()`
+        // copy any additional config
+        if (additionalConfig != null) {
+            project.copy(c -> {
+                c.from(additionalConfig.getAsFileTree());
+                c.into(getOutputDir());
+            });
+        }
     }
 
     /**

buildSrc/src/main/java/org/elasticsearch/gradle/test/rest/CopyRestTestsTask.java

@@ -58,6 +58,7 @@ public class CopyRestTestsTask extends DefaultTask {
     String sourceSetName;
     Configuration coreConfig;
     Configuration xpackConfig;
+    Configuration additionalConfig;
 
     private final PatternFilterable corePatternSet;
     private final PatternFilterable xpackPatternSet;
@@ -104,10 +105,14 @@ public FileTree getInputDir() {
                 coreFileTree = coreConfig.getAsFileTree(); // jar file
             }
         }
-        ConfigurableFileCollection fileCollection = getProject().files(coreFileTree, xpackFileTree);
+        ConfigurableFileCollection fileCollection = additionalConfig == null
+            ? getProject().files(coreFileTree, xpackFileTree)
+            : getProject().files(coreFileTree, xpackFileTree, additionalConfig.getAsFileTree());
 
         // copy tests only if explicitly requested
-        return includeCore.get().isEmpty() == false || includeXpack.get().isEmpty() == false ? fileCollection.getAsFileTree() : null;
+        return includeCore.get().isEmpty() == false || includeXpack.get().isEmpty() == false || additionalConfig != null
+            ? fileCollection.getAsFileTree()
+            : null;
     }
 
     @OutputDirectory
@@ -158,6 +163,14 @@ void copy() {
                 c.include(xpackPatternSet.getIncludes());
             });
         }
+        // TODO: once https://github.com/elastic/elasticsearch/pull/62968 lands ensure that this uses `getFileSystemOperations()`
+        // copy any additional config
+        if (additionalConfig != null) {
+            project.copy(c -> {
+                c.from(additionalConfig.getAsFileTree());
+                c.into(getOutputDir());
+            });
+        }
     }
 
     private Optional<SourceSet> getSourceSet() {