src/main/java/org/ucmtwine/parameter/Parameter.java
public String getStringValue(DataBinder binder) {
    // binder can't get a non existent param
    if (this.name == null || this.name.equals("")) {
      return null;
    }

    String value = (String) binder.getLocal(this.name);

    if (value == null && this.required) {
      throw new IllegalArgumentException("Parameter " + name + " is required");
    }

    return value;
  }
public String getStringValue(DataBinder binder) {
    // binder can't get a non existent param
    if (this.name == null || this.name.equals("")) {
      return null;
    }

    String value = (String) binder.getLocal(this.name);

    if (value == null && this.required) {
      throw new IllegalArgumentException("Parameter " + name + " is required");
    }

    return value;
  }
Get the string value from binder.