code: public SQLMergeClause addBatch() {
          if (!configuration.getTemplates().isNativeMerge()) {
              throw new IllegalStateException("batch only supported for databases that support native merge");
          }
  
          batches.add(new SQLMergeBatch(keys, columns, values, subQuery));
          columns.clear();
          values.clear();
          keys.clear();
          subQuery = null;
          return this;
      }
docs: Add the current state of bindings as a batch item
  
  @return the current object