code: public PreferredValueMakersRegistry addConstructorParameterMaker(Class ownerType, int argIndex, Maker<?> maker) {
          Preconditions.checkNotNull(ownerType);
          Preconditions.checkArgument(argIndex >= 0);
          makers.put(Matchers.equalTo(String.format(Settable.FULL_NAME_FORMAT, ownerType.getName(), "arg" + argIndex)), maker);
          return this;
      }
docs: Add a constructor parameter maker to a class type.
  i.e. with:
  <pre>
  {@code
  
  Class Person {
  Person(String name, int age)
  }
  }
  </pre>
  You could define a custom maker for name as (Person.class, 0, myNameMaker)
  
  @param ownerType
  the class that owns the field.
  @param argIndex
  constructor parameter index (0 based)
  @param maker
  custom maker
  @return this