code: public ModifyVpcEndpointRequest withAddSubnetIds(String... addSubnetIds) {
          if (this.addSubnetIds == null) {
              setAddSubnetIds(new com.amazonaws.internal.SdkInternalList<String>(addSubnetIds.length));
          }
          for (String ele : addSubnetIds) {
              this.addSubnetIds.add(ele);
          }
          return this;
      }
docs: <p>
  (Interface endpoint) One or more subnet IDs in which to serve the endpoint.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setAddSubnetIds(java.util.Collection)} or {@link #withAddSubnetIds(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param addSubnetIds
  (Interface endpoint) One or more subnet IDs in which to serve the endpoint.
  @return Returns a reference to this object so that method calls can be chained together.