code: public static void setColorsThumb(TextView initialsView, int backgroundColor, int strokeColor) {
          GradientDrawable drawable = (GradientDrawable) initialsView.getResources().getDrawable(R.drawable.boxsdk_thumb_background);
          drawable.setColorFilter(backgroundColor, PorterDuff.Mode.MULTIPLY);
          if (Build.VERSION.SDK_INT > Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1) {
              drawable.setStroke(3, strokeColor);
              initialsView.setBackground(drawable);
          } else {
              drawable.setStroke(3, strokeColor);
              initialsView.setBackgroundDrawable(drawable);
          }
      }
docs: Sets the the background thumb color for the account view to one of the material colors
  
  @param initialsView view where the thumbs will be shown