Compiling this code:

public class X {
    public class Y {
    }
    Y foo() {
        Y goo() {
            return new Y();
        }
        return goo();
    }
    public static void main(String [] args) {
        Y y = new X().foo();
        System.out.println("y = " + y);
    }
}

results in:

java.lang.ClassCastException: class com.sun.tools.javac.comp.LambdaToMethod$LambdaAnalyzerPreprocessor$LocalMethodTranslationContext cannot be cast to class com.sun.tools.javac.comp.LambdaToMethod$LambdaAnalyzerPreprocessor$LambdaTranslationContext (com.sun.tools.javac.comp.LambdaToMethod$LambdaAnalyzerPreprocessor$LocalMethodTranslationContext and com.sun.tools.javac.comp.LambdaToMethod$LambdaAnalyzerPreprocessor$LambdaTranslationContext are in module jdk.compiler of loader 'app')
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.visitNewClass(LambdaToMethod.java:657)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCNewClass.accept(JCTree.java:1791)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.visitReturn(TreeTranslator.java:274)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1648)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:70)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.visitBlock(TreeTranslator.java:167)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1029)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.visitMethodDef(LambdaToMethod.java:492)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:875)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:70)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.visitBlock(TreeTranslator.java:167)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1029)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.visitMethodDef(TreeTranslator.java:150)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.visitMethodDef(LambdaToMethod.java:500)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:875)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:70)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.visitClassDef(TreeTranslator.java:139)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.visitClassDef(LambdaToMethod.java:302)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:783)
at jdk.compiler/com.sun.tools.javac.tree.TreeTranslator.translate(TreeTranslator.java:58)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:262)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translate(LambdaToMethod.java:255)
at jdk.compiler/com.sun.tools.javac.comp.LambdaToMethod.translateTopLevelClass(LambdaToMethod.java:282)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.desugar(JavaCompiler.java:1602)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.desugar(JavaCompiler.java:1438)
at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:973)
at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:318)
at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:176)
at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)