code: public AccountAggregationSource withAccountIds(String... accountIds) {
          if (this.accountIds == null) {
              setAccountIds(new com.amazonaws.internal.SdkInternalList<String>(accountIds.length));
          }
          for (String ele : accountIds) {
              this.accountIds.add(ele);
          }
          return this;
      }
docs: <p>
  The 12-digit account ID of the account being aggregated.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setAccountIds(java.util.Collection)} or {@link #withAccountIds(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param accountIds
  The 12-digit account ID of the account being aggregated.
  @return Returns a reference to this object so that method calls can be chained together.