### Question:
LambdaLoggerPlainImpl implements LambdaLogger { @Override public Logger getUnderlyingLogger() { return underlyingLogger; } LambdaLoggerPlainImpl(Logger underlyingLogger); @Override Logger getUnderlyingLogger(); @Override void doLog(Marker marker, Level level, Supplier<String> msgSupplier, Throwable t); @Override void doLog(Marker marker, Level level, String format, Supplier<?>[] argSuppliers, Throwable t); @Override void doLog(Marker marker, Level level, String format, Object[] arguments, Throwable t);  }### Answer:
@Test public void getUnderlyingLogger() throws Exception { assertThat(lambdaLogger.getUnderlyingLogger()).isSameAs(underlyingLogger); }