public RoundingParams setPadding(float padding) {
    Preconditions.checkArgument(padding >= 0, "the padding cannot be < 0");
    mPadding = padding;
    return this;
  }
Sets the padding on rounded drawable. Works only with {@code RoundingMethod.BITMAP_ONLY}

@param padding the padding in pixels
drawee/src/main/java/com/facebook/drawee/generic/RoundingParams.java