code: public java.util.List<DBSubnetGroup> getDBSubnetGroups() {
          if (dBSubnetGroups == null) {
              dBSubnetGroups = new com.amazonaws.internal.SdkInternalList<DBSubnetGroup>();
          }
          return dBSubnetGroups;
      }
docs: <p>
  A list of <a>DBSubnetGroup</a> instances.
  </p>
  
  @return A list of <a>DBSubnetGroup</a> instances.