Code:

$ cat Test.java

public class Test {

    interface Constructor {
        MyTest execute();
    }

    class MyTest {
        MyTest() { System.out.println("Constructor executed"); }
    }

    public Constructor getConstructor() {
        return getConstructor(() -> { return MyTest::new; });
    }

    public static void main(String argv[]) {
        Test t = new Test();
        MyTest mytest = t.getConstructor().execute();
    }

    Constructor getConstructor(Wrapper arg) {
        return arg.unwrap();
    }

    interface Wrapper {
        Constructor unwrap();
    }
}

Generates NullPointerException on compilation:

$ javac Test.java
An exception has occurred in the compiler (1.9.0-internal). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.NullPointerException
at com.sun.tools.javac.jvm.Code.emitop0(Code.java:563)
at com.sun.tools.javac.jvm.Items$SelfItem.load(Items.java:367)
at com.sun.tools.javac.jvm.Gen.genArgs(Gen.java:959)
at com.sun.tools.javac.jvm.Gen.visitApply(Gen.java:1898)
at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1459)
at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:940)
at com.sun.tools.javac.jvm.Gen.visitReturn(Gen.java:1856)
at com.sun.tools.javac.tree.JCTree$JCReturn.accept(JCTree.java:1378)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:730)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:765)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:751)
at com.sun.tools.javac.jvm.Gen.genStats(Gen.java:802)
at com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1151)
at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:903)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:730)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:765)
at com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:1024)
at com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:987)
at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:772)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:730)
at com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2518)
at com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:744)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1571)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1535)
at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:906)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:865)
at com.sun.tools.javac.main.Main.compile(Main.java:521)
at com.sun.tools.javac.main.Main.compile(Main.java:381)
at com.sun.tools.javac.main.Main.compile(Main.java:370)
at com.sun.tools.javac.main.Main.compile(Main.java:361)
at com.sun.tools.javac.Main.compile(Main.java:56)
at com.sun.tools.javac.Main.main(Main.java:42)

Changing 'getConstructor()' method to implementation without lambda wrapper works good:

    public Constructor getConstructor() {
        return MyTest::new;
    }

$ javac Test.java
$ java Test
Constructor executed