public PolicyVariables addRuleVariablesEntry(String key, IPSet value) {
        if (null == this.ruleVariables) {
            this.ruleVariables = new java.util.HashMap<String, IPSet>();
        }
        if (this.ruleVariables.containsKey(key))
            throw new IllegalArgumentException("Duplicated keys (" + key.toString() + ") are provided.");
        this.ruleVariables.put(key, value);
        return this;
    }
Add a single RuleVariables entry

@see PolicyVariables#withRuleVariables
@returns a reference to this object so that method calls can be chained together.
aws-java-sdk-networkfirewall/src/main/java/com/amazonaws/services/networkfirewall/model/PolicyVariables.java