To be able to deal with situations where we want to use a field of a superclass as a parameter, but do only have access to this field via get- and set-methods (due to restricted visibility or even because the value is not stored directly in a field, but by some other mechanism), we have to specify the get-method in the declaration of the parameter:

module X { private float a; float getA(){} void setA(float a){} };  // private field
 
module Y(float a return getA()) extends X.(setA(a));
 
//is equivalent to:
class Y extends X {
 
  public Y(float val){
    super();
    setA(val);
  }
 
 ... // pattern
}

As you see the method getA() is not actually used. It only serve as placeholder for the syntax. The method has to be declared though.