code: public JobGetHeaders withLastModified(DateTime lastModified) {
          if (lastModified == null) {
              this.lastModified = null;
          } else {
              this.lastModified = new DateTimeRfc1123(lastModified);
          }
          return this;
      }
docs: Set the time at which the resource was last modified.
  
  @param lastModified the lastModified value to set
  @return the JobGetHeaders object itself.