code: public @NotNull DoubleArrayAssert isEqualTo(@Nullable double[] expected, @NotNull Delta delta) {
      checkNotNull(delta);
      if (actual == expected) {
        return this;
      }
      if (actual == null || expected == null) {
        throw failureWhenNotEqual(expected, delta);
      }
      int length = expected.length;
      if (actual.length != length) {
        failureWhenNotEqual(expected, delta);
      }
      for (int i = 0; i < length; i++) {
        if (!equals(expected[i], actual[i], delta)) {
          failureWhenNotEqual(expected, delta);
        }
      }
      return this;
    }
docs: Verifies that the actual {@code double} array is equal to the given array, within a positive delta.
  
  @param expected the given array to compare the actual array to.
  @param delta    the given delta.
  @return this assertion object.
  @throws NullPointerException if {@code delta} is {@code null}.
  @throws AssertionError       if the actual {@code double} array is not equal to the given one.
  @since 1.1