code: public static String getSingleFamilyName(FilterAdapterContext context) {
      Preconditions.checkState(
          context.getScan().numFamilies() == 1,
          "Cannot getSingleFamilyName() unless there is exactly 1 family.");
      return Bytes.toString(context.getScan().getFamilies()[0]);
    }
docs: Extract a single family name from a FilterAdapterContext. Throws if there
  is not exactly 1 family present in the scan.
  
  @param context a {@link com.google.cloud.bigtable.hbase.adapters.filters.FilterAdapterContext} object.
  @return a {@link java.lang.String} object.