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

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