### Question:
StackFrame { public void appendFileName(StringBuilder replaceBuilder) { if (className != null) { int fileNameEnd = className.indexOf('$'); if (fileNameEnd < 0) { fileNameEnd = className.length(); } int classNameStart = className.lastIndexOf('.'); if (classNameStart < fileNameEnd && fileNameEnd <= className.length()) { replaceBuilder.append(className, classNameStart + 1, fileNameEnd); replaceBuilder.append(".java"); } else { replaceBuilder.append("<Unknown>"); } } else { replaceBuilder.append("<Unknown>"); } } StackFrame(@Nullable String className, String methodName); static StackFrame of(@Nullable String className, String methodName); @Nullable String getClassName(); String getMethodName(); void appendSimpleClassName(StringBuilder sb); void appendFileName(StringBuilder replaceBuilder); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString();  }### Answer:
@Test void testAppendFileName() { assertThat(getFileName("Baz")).isEqualTo("Baz.java"); assertThat(getFileName("foo.bar.Baz")).isEqualTo("Baz.java"); assertThat(getFileName("foo.bar.Baz$Qux")).isEqualTo("Baz.java"); assertThat(getFileName("baz")).isEqualTo("baz.java"); }