code: public void setCustomizableAttributes(com.google.api.ads.admanager.axis.v201811.CustomizableAttributes customizableAttributes) {
          this.customizableAttributes = customizableAttributes;
      }
docs: Sets the customizableAttributes value for this ProposalLineItemConstraints.
  
  @param customizableAttributes   * Specifies what targeting or attributes for the created {@link
  ProposalLineItem}
  are customizable.
  
  <p>This attribute is read-only.