code: public static Map<String, ClassNode> getAssocationMap(ClassNode classNode, String associationType) {
          PropertyNode property = classNode.getProperty(associationType);
          Map<String, ClassNode> associationMap = new HashMap<String, ClassNode>();
          if (property != null && property.isStatic()) {
              Expression e = property.getInitialExpression();
              if (e instanceof MapExpression) {
                  MapExpression me = (MapExpression) e;
                  for (MapEntryExpression mee : me.getMapEntryExpressions()) {
                      String key = mee.getKeyExpression().getText();
                      Expression valueExpression = mee.getValueExpression();
                      if (valueExpression instanceof ClassExpression) {
                          associationMap.put(key, valueExpression.getType());
                      }
                  }
              }
          }
          return associationMap;
      }
docs: Returns a map containing the names and types of the given association type. eg. GrailsDomainClassProperty.HAS_MANY
  @param classNode The target class ndoe
  @param associationType The associationType
  @return A map