public StartGameSessionPlacementRequest withGameProperties(GameProperty... gameProperties) {
        if (this.gameProperties == null) {
            setGameProperties(new java.util.ArrayList<GameProperty>(gameProperties.length));
        }
        for (GameProperty ele : gameProperties) {
            this.gameProperties.add(ele);
        }
        return this;
    }
<p>
A set of key-value pairs that can store custom data in a game session. For example:
<code>{"Key": "difficulty", "Value": "novice"}</code>.
</p>
<p>
<b>NOTE:</b> This method appends the values to the existing list (if any). Use
{@link #setGameProperties(java.util.Collection)} or {@link #withGameProperties(java.util.Collection)} if you want
to override the existing values.
</p>

@param gameProperties
       A set of key-value pairs that can store custom data in a game session. For example:
       <code>{"Key": "difficulty", "Value": "novice"}</code>.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-gamelift/src/main/java/com/amazonaws/services/gamelift/model/StartGameSessionPlacementRequest.java