Initial commit (#362).

src/main/java/org/gitlab4j/api/webhook/IssueChanges.java

+package org.gitlab4j.api.webhook;
+
+import java.util.Date;
+
+public class IssueChanges extends EventChanges {
+
+    private ChangeContainer<Date> dueDate;
+    private ChangeContainer<Boolean> confidential;
+
+    public ChangeContainer<Date> getDueDate() {
+        return dueDate;
+    }
+
+    public void setDueDate(ChangeContainer<Date> dueDate) {
+        this.dueDate = dueDate;
+    }
+
+    public ChangeContainer<Boolean> getConfidential() {
+        return confidential;
+    }
+
+    public void setConfidential(ChangeContainer<Boolean> confidential) {
+        this.confidential = confidential;
+    }
+}

src/main/java/org/gitlab4j/api/webhook/MergeRequestChanges.java

+package org.gitlab4j.api.webhook;
+
+public class MergeRequestChanges extends EventChanges {
+
+    private ChangeContainer<String> mergeStatus;
+
+    public ChangeContainer<String> getMergeStatus() {
+        return mergeStatus;
+    }
+
+    public void setMergeStatus(ChangeContainer<String> mergeStatus) {
+        this.mergeStatus = mergeStatus;
+    }
+}