code: public Color getColorForBond(IBond bond, RendererModel model) {
          if (this.overrideColor != null) {
              return overrideColor;
          }
  
          Color color = model.getParameter(ColorHash.class).getValue().get(bond);
          if (color == null) {
              return model.getParameter(DefaultBondColor.class).getValue();
          } else {
              return color;
          }
      }
docs: Determine the color of a bond, returning either the default color,
  the override color or whatever is in the color hash for that bond.
  
  @param bond the bond we are generating an element for
  @param model the rendering model
  @return the color to paint the bond