Add Java gen as a bridge functionality (#3184)

This pull request adds the ability to generate the Java SDK via
`pulumi-tfgen-foo --java`.

It additionally introduces a breaking change to the `info.Java` struct
by adding an `Overlay` field. I believe this is a breaking change we can
afford to take, as the struct already advertises that its use is for
overlay functionality, but this was never implemented. We can also
choose to not support overlays via the bridge for Java for now, since
I'm unaware of any of our bridged providers having them.

Sample changes for pulumi-random:
pulumi/pulumi-random#1863

Sample changes in pulumi-aws (warning; very noisy, as the
autogenerated-file-warning has changed):
pulumi/pulumi-aws#5817

TL;DR:
- We see a new, empty `Pulumi.yaml` file, same as for the other SDKs
- Autogenerated warning has changed
- A nice bonus: Java inline docs no longer emit spurious
PulumiCodeChooser tags, as the bridge filters that for us now.
- Functional code remains the same

---
- **Add Java as a valid bridge language for SDK generation**
- **Add overlay info for Java**

Fixes #3183

Author: guineveresaenger

pkg/tfbridge/info/info.go

@@ -914,11 +914,10 @@ type CSharp struct {
 	RespectSchemaVersion bool
 }
 
-// See https://github.com/pulumi/pulumi-java/blob/main/pkg/codegen/java/package_info.go#L35C1-L108C1 documenting
-// supported options.
+// Java contains optional overlay information for Java code-generation.
 type Java struct {
-	BasePackage string // the Base package for the Java SDK
-
+	BasePackage string   // the Base package for the Java SDK
+	Overlay     *Overlay // optional overlay information for augmented code-generation.
 	// If set to "gradle" enables a generation of a basic set of
 	// Gradle build files.
 	BuildFiles string

pkg/tfgen/docs.go

@@ -2031,6 +2031,8 @@ func genLanguageToSlice(input Language) []string {
 		return []string{convert.LanguageCSharp}
 	case Golang:
 		return []string{convert.LanguageGo}
+	case Java:
+		return []string{convert.LanguageJava}
 	case PCL:
 		return []string{convert.LanguagePulumi}
 	case Schema, RegistryDocs:

pkg/tfgen/generate.go

@@ -91,6 +91,7 @@ const (
 	NodeJS Language = "nodejs"
 	Python Language = "python"
 	CSharp Language = "dotnet"
+	Java   Language = "java"
 	Schema Language = "schema"
 	PCL    Language = "pulumi"
 	// RegistryDocs
@@ -105,7 +106,7 @@ const (
 
 func (l Language) shouldConvertExamples() bool {
 	switch l {
-	case Golang, NodeJS, Python, CSharp, Schema, PCL:
+	case Golang, NodeJS, Python, CSharp, Java, Schema, PCL:
 		return true
 	}
 	return false
@@ -292,12 +293,25 @@ func (l Language) emitSDK(pkg *pschema.Package, info tfbridge.ProviderInfo, root
 			return nil, err
 		}
 		return runPulumiPackageGenSDK(l, pkg, extraFiles)
+	case Java:
+		if psi := info.Java; psi != nil && psi.Overlay != nil {
+			extraFiles, err = getOverlayFiles(psi.Overlay, ".java", root)
+			if err != nil {
+				return nil, err
+			}
+		}
+		err = cleanDir(root, "", nil)
+		if err != nil && !os.IsNotExist(err) {
+			return nil, err
+		}
+		return runPulumiPackageGenSDK(l, pkg, extraFiles)
+
 	default:
 		return nil, fmt.Errorf("%v does not support SDK generation", l)
 	}
 }
 
-var AllLanguages = []Language{Golang, NodeJS, Python, CSharp}
+var AllSDKLanguages = []Language{Golang, NodeJS, Python, CSharp, Java}
 
 // pkg is a directory containing one or more modules.
 type pkg struct {
@@ -935,7 +949,7 @@ func NewGenerator(opts GeneratorOptions) (*Generator, error) {
 
 	// Ensure the language is valid.
 	switch lang {
-	case Golang, NodeJS, Python, CSharp, Schema, PCL, RegistryDocs:
+	case Golang, NodeJS, Python, CSharp, Java, Schema, PCL, RegistryDocs:
 		// OK
 	default:
 		return nil, fmt.Errorf("unrecognized language runtime: %s", lang)
@@ -1745,6 +1759,10 @@ func (g *Generator) gatherOverlays() (moduleMap, error) {
 		if csharpinfo := g.info.CSharp; csharpinfo != nil {
 			overlay = csharpinfo.Overlay
 		}
+	case Java:
+		if javainfo := g.info.Java; javainfo != nil {
+			overlay = javainfo.Overlay
+		}
 	case Schema, PCL, RegistryDocs:
 		// N/A
 	default:

pkg/tfgen/main.go

@@ -89,7 +89,7 @@ func newTFGenCmd(pkg string, version string, prov tfbridge.ProviderInfo,
 			"and generate all of the Pulumi metadata necessary to consume the resources.\n" +
 			"\n" +
 			"<LANGUAGE> indicates which language/runtime to target; the current supported set of\n" +
-			"languages is " + fmt.Sprintf("%v", AllLanguages) + ".\n" +
+			"languages is " + fmt.Sprintf("%v", AllSDKLanguages) + ".\n" +
 			"\n" +
 			"Note that there is no custom Pulumi provider code required, because the generated\n" +
 			"provider plugin is metadata-driven and thus works against all Terraform providers.\n",