Improve rendering fidelity of the AST-to-source transpiler

spock-core/src/main/groovy/spock/util/SourceToAstNodeAndSourceTranspiler.groovy

@@ -542,6 +542,11 @@ class AstNodeToScriptVisitor extends CompilationUnit.PrimaryClassNodeOperation i
         }
         first = false
         print it.name
+        // a concrete type argument may carry its own nested type arguments (e.g. Tuple2<Integer, Integer>);
+        // recurse so they are not dropped. Placeholders (T) and wildcards (?) never carry them.
+        if (!it.placeholder && !it.wildcard) {
+          visitGenerics it.type?.genericsTypes
+        }
         if (it.upperBounds) {
           print ' extends '
           boolean innerFirst = true

spock-specs/src/test/groovy/org/spockframework/smoke/ast/AstSpec.groovy

@@ -136,6 +136,20 @@ class Foo {
     snapshotter.assertThat(result.source).matchesSnapshot()
   }
 
+  def "nested generic type arguments are rendered faithfully"() {
+    when:
+    def result = compiler.transpile('''
+class Foo {
+  Map<String, List<Integer>> nested() { null }
+  List<? extends Number> upperBounded() { null }
+  def <T extends CharSequence> List<T> methodTypeParameter() { null }
+}
+''', EnumSet.of(Show.METHODS))
+
+    then:
+    snapshotter.assertThat(result.source).matchesSnapshot()
+  }
+
   def "enums"() {
     given:
     // groovy 4 renders differently

spock-specs/src/test/resources/snapshots/org/spockframework/smoke/ast/AstSpec/nested_generic_type_arguments_are_rendered_faithfully.groovy

@@ -0,0 +1,11 @@
+public java.util.Map<String, List<Integer>> nested() {
+    null
+}
+
+public java.util.List<? extends java.lang.Number> upperBounded() {
+    null
+}
+
+public <T extends java.lang.CharSequence> java.util.List<T> methodTypeParameter() {
+    null
+}