public SendAutomationSignalRequest addPayloadEntry(String key, java.util.List<String> value) {
        if (null == this.payload) {
            this.payload = new java.util.HashMap<String, java.util.List<String>>();
        }
        if (this.payload.containsKey(key))
            throw new IllegalArgumentException("Duplicated keys (" + key.toString() + ") are provided.");
        this.payload.put(key, value);
        return this;
    }
Add a single Payload entry

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