public DefaultIssue setLine(@Nullable Integer l) {
    Preconditions.checkArgument(l == null || l > 0, "Line must be null or greater than zero (got %s)", l);
    this.line = l;
    return this;
  }
@Test
  void setLine_whenLineIsNegative_shouldThrowException() {
    int anyNegativeValue = Integer.MIN_VALUE;
    assertThatThrownBy(() -> issue.setLine(anyNegativeValue))
      .isInstanceOf(IllegalArgumentException.class)
      .hasMessage(String.format("Line must be null or greater than zero (got %s)", anyNegativeValue));
  }