public java.util.List<InstanceDefinition> getInstanceDefinitions() {
        return instanceDefinitions;
    }
<p>
The Amazon EC2 instance types and sizes to use in the Auto Scaling group. The instance definitions must specify
at least two different instance types that are supported by Amazon GameLift FleetIQ. For more information on
instance types, see <a href="https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html">EC2
Instance Types</a> in the <i>Amazon Elastic Compute Cloud User Guide</i>. You can optionally specify capacity
weighting for each instance type. If no weight value is specified for an instance type, it is set to the default
value "1". For more information about capacity weighting, see <a
href="https://docs.aws.amazon.com/autoscaling/ec2/userguide/asg-instance-weighting.html"> Instance Weighting for
Amazon EC2 Auto Scaling</a> in the Amazon EC2 Auto Scaling User Guide.
</p>

@return The Amazon EC2 instance types and sizes to use in the Auto Scaling group. The instance definitions must
        specify at least two different instance types that are supported by Amazon GameLift FleetIQ. For more
        information on instance types, see <a
        href="https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html">EC2 Instance Types</a> in
        the <i>Amazon Elastic Compute Cloud User Guide</i>. You can optionally specify capacity weighting for
        each instance type. If no weight value is specified for an instance type, it is set to the default value
        "1". For more information about capacity weighting, see <a
        href="https://docs.aws.amazon.com/autoscaling/ec2/userguide/asg-instance-weighting.html"> Instance
        Weighting for Amazon EC2 Auto Scaling</a> in the Amazon EC2 Auto Scaling User Guide.
aws-java-sdk-gamelift/src/main/java/com/amazonaws/services/gamelift/model/CreateGameServerGroupRequest.java