Check java lambda instance is singleton.

lambdainstance.java

String foo() {
    return "abc";
}

String foo(Supplier<String> s) {
    System.out.println(s);
    return "abc " + s.get();
}

@Test
public void sample() {
    IntStream.range(1, 10)
             .forEach(i -> foo(this::foo));
}

// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@6b53e23f
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@400cff1a
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@275710fc
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@525f1e4e
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@75f9eccc
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@52aa2946
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@4de5031f
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@67e2d983
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@5d47c63f

   static String bar() {
        return "abc";
    }

    @Test
    public void lambdaStatic() {
        IntStream.range(1, 10)
                 .forEach(i -> foo(LambdaInstance::bar));
    }
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
// playground.LambdaInstance$$Lambda$43/0x00000008000e8040@62e136d3
```