public void setPlacementId(String placementId) {
        this.placementId = placementId;
    }
<p>
A unique identifier to assign to the new game session placement. This value is developer-defined. The value must
be unique across all Regions and cannot be reused.
</p>

@param placementId
       A unique identifier to assign to the new game session placement. This value is developer-defined. The
       value must be unique across all Regions and cannot be reused.
aws-java-sdk-gamelift/src/main/java/com/amazonaws/services/gamelift/model/StartGameSessionPlacementRequest.java