public String getEC2SecurityGroupId() {
        return this.eC2SecurityGroupId;
    }
<p>
Id of the EC2 security group to authorize. For VPC DB security groups, <code>EC2SecurityGroupId</code> must be
provided. Otherwise, <code>EC2SecurityGroupOwnerId</code> and either <code>EC2SecurityGroupName</code> or
<code>EC2SecurityGroupId</code> must be provided.
</p>

@return Id of the EC2 security group to authorize. For VPC DB security groups, <code>EC2SecurityGroupId</code>
        must be provided. Otherwise, <code>EC2SecurityGroupOwnerId</code> and either
        <code>EC2SecurityGroupName</code> or <code>EC2SecurityGroupId</code> must be provided.
aws-java-sdk-rds/src/main/java/com/amazonaws/services/rds/model/AuthorizeDBSecurityGroupIngressRequest.java