VRC0016: The method specified for SendCustomEvent must be public

The method specified for SendCustomEvent must be public

Example

Code with Diagnostic

using UdonSharp;

class TestBehaviour0 : UdonSharpBehaviour
{
    private TestBehaviour1 _behaviour;

    public override void Interact()
    {
        _behaviour.SendCustomEvent("TestMethod");
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    }
}

class TestBehaviour1 : UdonSharpBehaviour
{
    private void TestMethod() {}
}

Code with Fix

// NOT YET PROVIDED