code: public FieldDeclaration getFieldNode(String name, String signature) {
      for (EntityDeclaration node : type.getMembers()) {
        if (node.getEntityType() == EntityType.FIELD) {
          FieldDeclaration field = (FieldDeclaration) node;
          if (field.getName().equals(name)
              && signature(field.getReturnType()).equals(signature)) {
            return field;
          }
        }
      }
      return null;
    }
docs: Returns the Procyon field definition for a specified variable,
  or null if not found.