code: public com.google.api.ads.adwords.axis.v201809.cm.AssetLink[] getSquareMarketingImages() {
          return squareMarketingImages;
      }
docs: Gets the squareMarketingImages value for this MultiAssetResponsiveDisplayAd.
  
  @return squareMarketingImages   * Square marketing image to be used in the ad. This image may
  be used when a square aspect ratio
  is more appropriate than the aspect ratio of the
  {@link #marketingImage} image. This ad format
  does not allow the creation of an imageAsset using
  the ImageAsset.imageData field. An
  imageAsset must first be created using the AssetService,
  and ImageAsset.assetId must be
  populated in this field. Valid image types are
  GIF, JPEG, and PNG. The minimum size is 300x300
  the aspect ratio must be 1:1 (+-1%). One squareMarketingImage
  is required. Support up to 15
  with marketingImages.
  <span class="constraint Selectable">This field
  can be selected using the value "MultiAssetResponsiveDisplayAdSquareMarketingImages".</span>
  <span class="constraint Required">This field is required and should
  not be {@code null} when it is contained within {@link Operator}s
  : ADD.</span>