code: public UpdateRequest multi(final boolean isMulti) {
          if (isMulti && updateType == Type.REPLACE) {
              throw new IllegalArgumentException("Replacements can not be multi");
          }
          this.isMulti = isMulti;
          return this;
      }
docs: Sets whether this will update all documents matching the query filter.
  
  @param isMulti whether this will update all documents matching the query filter
  @return this