src/main/java/org/helm/notation2/parser/notation/polymer/MonomerNotation.java
public void setAnnotation(String str) {
    if (str != null) {
      annotation = str;
      isAnnotationHere = true;
    } else {
      annotation = null;
      isAnnotationHere = false;
    }
  }
public void setAnnotation(String str) {
    if (str != null) {
      annotation = str;
      isAnnotationHere = true;
    } else {
      annotation = null;
      isAnnotationHere = false;
    }
  }
method to add annotation to this monomer

@param str annotation