code: public void setBuiltInCreativePlaceholders(com.google.api.ads.admanager.axis.v201805.CreativePlaceholder[] builtInCreativePlaceholders) {
          this.builtInCreativePlaceholders = builtInCreativePlaceholders;
      }
docs: Sets the builtInCreativePlaceholders value for this ProposalLineItemConstraints.
  
  @param builtInCreativePlaceholders   * The built-in {@link CreativePlaceholder creative placeholders}
  for the created
  {@link ProposalLineItem}.
  
  <p>This attribute is read-only.