CFID-290: Add equals and hashcode to UaaPrincipal

Change-Id: Ibcecae9216c783cc1856b01089b4c29bb9f3f4de

common/src/main/java/org/cloudfoundry/identity/uaa/authentication/UaaPrincipal.java

@@ -46,4 +46,27 @@ public String getEmail() {
 		return email;
 	}
 
+	/**
+	 * Returns {@code true} if the supplied object is a {@code UAAPrincipal} instance with the
+	 * same {@code id} value.
+	 * <p>
+	 * In other words, the objects are equal if they have the same user id, representing the
+	 * same principal.
+	 */
+	@Override
+	public boolean equals(Object rhs) {
+		if (rhs instanceof UaaPrincipal) {
+			return id.equals(((UaaPrincipal) rhs).id);
+		}
+		return false;
+	}
+
+	/**
+	 * Returns the hashcode of the {@code id}.
+	 */
+	@Override
+	public int hashCode() {
+		return id.hashCode();
+	}
+
 }