code: public DescribeRegionsRequest withRegionNames(String... regionNames) {
          if (this.regionNames == null) {
              setRegionNames(new com.amazonaws.internal.SdkInternalList<String>(regionNames.length));
          }
          for (String ele : regionNames) {
              this.regionNames.add(ele);
          }
          return this;
      }
docs: <p>
  The names of the regions.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setRegionNames(java.util.Collection)} or {@link #withRegionNames(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param regionNames
  The names of the regions.
  @return Returns a reference to this object so that method calls can be chained together.