Add a test to verify that analysis server code generation is up to date.

pkg/analysis_server/tool/spec/codegen_java.dart

Index: pkg/analysis_server/tool/spec/codegen_java.dart
diff --git a/pkg/analysis_server/tool/spec/codegen_java.dart b/pkg/analysis_server/tool/spec/codegen_java.dart
index f464eeec52cc3e210193505fe678231da0854b8b..2e7d9bb90504dcb2597ac173a2d891a3a50d7b1c 100644
--- a/pkg/analysis_server/tool/spec/codegen_java.dart
+++ b/pkg/analysis_server/tool/spec/codegen_java.dart
@@ -7,10 +7,9 @@
  */
 library CodegenJava;
 
-import 'dart:io';
-
 import 'api.dart';
 import 'codegen_tools.dart';
+import 'from_html.dart';
 import 'to_html.dart';
 
 /**
@@ -152,10 +151,12 @@ class _CodegenJavaState {
 }
 
 /**
- * Use [visitor] to create Java code and output it to [path].
+ * Create a [GeneratedFile] that creates Java code and outputs it to [path].
+ * [path] uses Posix-style path separators regardless of the OS.
  */
-void createJavaCode(String path, CodegenJavaVisitor visitor) {
-  String code = visitor.collectCode(visitor.visitApi);
-  File outputFile = new File(path);
-  outputFile.writeAsStringSync(code);
+GeneratedFile javaGeneratedFile(String path, CodegenJavaVisitor createVisitor(Api api)) {
+  return new GeneratedFile(path, () {
+    CodegenJavaVisitor visitor = createVisitor(readApi());
+    return visitor.collectCode(visitor.visitApi);
+  });
 }