void () { doTest(""" java.lang.IllegalArgumentException: Argument for @NotNull parameter 'y' of foo/bar/Test.callee must not be null \tat foo.bar.Test.$$$reportNull$$$0(Test.java) \tat foo.bar.Test.callee(Test.java)""", "Find why 'b' could be null", """ package foo.bar; class Test { void caller(String a, String b, String c) { callee(a, b, c); } void callee(String x, String y, String z) {} }"""); }