Fix TypeDecl code to include abstract/final and generics #5726 (#5728)

* Fix TypeDecl code to include abstract/final and generics #5726

* Cycle through keywords

---------

Co-authored-by: maltek <1694194+maltek@users.noreply.github.com>
Co-authored-by: Malte Kraus <mkraus@qwiet.ai>

Author: ventusfortis

joern-cli/frontends/javasrc2cpg/src/main/scala/io/joern/javasrc2cpg/astcreation/declarations/AstForTypeDeclsCreator.scala

@@ -790,7 +790,6 @@ private[declarations] trait AstForTypeDeclsCreator { this: AstCreator =>
 
   private def codeForTypeDecl(typ: TypeDeclaration[?], isInterface: Boolean): String = {
     val codeBuilder = new mutable.StringBuilder()
-
     typ.getModifiers.asScala
       .foreach { modifier =>
         codeBuilder.append(modifier.getKeyword.asString())
@@ -807,6 +806,15 @@ private[declarations] trait AstForTypeDeclsCreator { this: AstCreator =>
     codeBuilder.append(classPrefix)
     codeBuilder.append(typ.getNameAsString)
 
+    val typeParameters = typ match {
+      case classOrInterface: ClassOrInterfaceDeclaration => classOrInterface.getTypeParameters.asScala
+      case recordDeclaration: RecordDeclaration          => recordDeclaration.getTypeParameters.asScala
+      case _                                             => Nil
+    }
+    if (typeParameters.nonEmpty) {
+      codeBuilder.append(typeParameters.mkString("<", ", ", ">"))
+    }
+
     codeBuilder.toString()
   }
 

joern-cli/frontends/javasrc2cpg/src/test/scala/io/joern/javasrc2cpg/querying/TypeDeclTests.scala

@@ -59,6 +59,18 @@ class NewTypeDeclTests extends JavaSrcCode2CpgFixture {
     }
   }
 
+  "type decl code" should {
+    "include abstract modifier and type parameters" in {
+      val cpg = code("""
+          |class BaseReq {}
+          |public abstract class GenericService<T extends BaseReq, R> {}
+          |""".stripMargin)
+
+      cpg.typeDecl.nameExact("GenericService").code.l shouldBe
+        List("public abstract class GenericService<T extends BaseReq, R>")
+    }
+  }
+
   "typedecls extending unresolved types available in imports should have inheritsFrom set" in {
     val cpg = code("""package io.vrooom.vulnerableapp;
         |