code: private static String getSetterName(Method m) {
          String name = m.getName();
          if (name.startsWith("set") && (name.length() >= 4)
                  && m.getReturnType().equals(void.class)
                  && (m.getParameterTypes().length == 1)
          ) {
              return Character.toLowerCase(name.charAt(3)) + name.substring(4);
          }
          return null;
      }
docs: Get setter name. "setName" -> "name"
  
  @param m Method object.
  @return Property name of this setter.