code: public com.google.api.ads.admanager.axis.v201805.DateTime getStartDateTime() {
          return startDateTime;
      }
docs: Gets the startDateTime value for this ProposalLineItem.
  
  @return startDateTime   * The date and time at which the line item associated with the
  {@code ProposalLineItem} is enabled to begin serving. This attribute
  is optional
  during creation, but required and must be in the future
  when it turns into a line item.
  The {@link DateTime#timeZoneID} is required if start
  date time is not {@code null}.
  This attribute becomes readonly once the {@code ProposalLineItem}
  has started delivering.