code: public com.google.api.ads.admanager.axis.v201805.ProposalLineItemConstraints getProductConstraints() {
          return productConstraints;
      }
docs: Gets the productConstraints value for this ProposalLineItem.
  
  @return productConstraints   * All the product constraints set for this {@code ProposalLineItem}.
  <span class="constraint Applicable">This attribute is applicable when:<ul><li>using
  programmatic guaranteed, using sales management.</li><li>not using
  programmatic, using sales management.</li></ul></span>
  <span class="constraint ReadOnly">This attribute is
  read-only when:<ul><li>using programmatic guaranteed, using sales
  management.</li><li>not using programmatic, using sales management.</li></ul></span>