Description of the problem / feature request:

When a test class uses the @DataProvider annotation on a private method, error-prone reports UnusedMethod.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

This is not a completely working example, it's a redacted version of one of the classes where this occurs in my project (which is unfortunately not open source so I can't just link to the actual class), but it should show the use case. In this case the UnusedMethod would be reported for the data method.

import static org.fest.assertions.api.Assertions.assertThat;

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;

public class MyTest {
  @Test(dataProvider = "data")
  public void testInputGivesCorrectOutput(String input, String expected) throws Exception {
    // given
    MyClass objectUnderTest = new MyClass();

    // when
    String actual = objectUnderTest.get();

    // then
    assertThat(actual).isEqualTo(expected);
  }

  @DataProvider
  private static Object[][] data() {
    return new Object[][] {
      {"input-1", "output-1"},
      {"input-2", "output-2"}
    };
  }
}

What version of Error Prone are you using?

2.3.4

Have you found anything relevant by searching the web?

No. For now I am just disabling this warning.