Fix unable to remove event participants once set (#83)

The participants list was defaulted to null, which meant when attempting to serialize the object, the value is discarded. Now the default is an empty list, so if the user empties the list of participants, the object will serialize that field to an empty list.

Author: mrashed-dev

CHANGELOG.md

@@ -14,6 +14,8 @@ This section contains changes that have been committed but not yet released.
 
 ### Fixed
 
+* Fixed issue where `Event` participants could never be entirely removed once set
+
 ### Removed
 
 ### Security

src/main/java/com/nylas/Event.java

@@ -253,6 +253,13 @@ public void addMetadata(String key, String value) {
 		this.metadata.put(key, value);
 	}
 
+	/**
+	 * Remove all metadata from the event
+	 */
+	public void clearMetadata() {
+		this.metadata.clear();
+	}
+
 	/**
 	 * Add one (or many) notifications to the event
 	 * @param notifications The notification(s) to append to the event's notification list
@@ -264,6 +271,13 @@ public void addNotification(Notification... notifications) {
 		this.notifications.addAll(Arrays.asList(notifications));
 	}
 
+	/**
+	 * Remove all notifications from the event
+	 */
+	public void clearNotifications() {
+		this.notifications.clear();
+	}
+
 	/**
 	 * Add one (or many) participants to the event
 	 * @param participants The participant(s) to append to the event's participant list
@@ -272,6 +286,13 @@ public void addParticipants(Participant... participants) {
 		this.participants.addAll(Arrays.asList(participants));
 	}
 
+	/**
+	 * Remove all participants from the event
+	 */
+	public void clearParticipants() {
+		this.participants.clear();
+	}
+
 	/**
 	 * Checks the validity of the event
 	 * @return If the event is valid
@@ -300,7 +321,7 @@ protected Map<String, Object> getWritableFields(boolean creation) {
 			}
 		}
 
-		List<Map<String, Object>> participantWritableFields = null;
+		List<Map<String, Object>> participantWritableFields = Collections.emptyList();
 		if(participants != null && !participants.isEmpty()) {
 			participantWritableFields = participants.stream()
 					.map(participant -> participant.getWritableFields(creation))