Address javax.websocket conflict

The org.eclipse.jetty:jetty-maven-plugin dependencies duplicate classes:

  +- org.eclipse.jetty:jetty-maven-plugin:jar:9.4.26.v20200117:compile
  |  +- org.eclipse.jetty.websocket:javax-websocket-server-impl:jar:9.4.26.v20200117:compile
  |  |  +- org.eclipse.jetty.websocket:javax-websocket-client-impl:jar:9.4.26.v20200117:compile
  |  |  |  \- javax.websocket:javax.websocket-client-api:jar:1.0:compile
  |  |  \- javax.websocket:javax.websocket-api:jar:1.0:compile
  |  +- org.eclipse.jetty.websocket:websocket-server:jar:9.4.26.v20200117:compile
  |  |  +- org.eclipse.jetty.websocket:websocket-common:jar:9.4.26.v20200117:compile
  |  |  |  \- org.eclipse.jetty.websocket:websocket-api:jar:9.4.26.v20200117:compile
  |  |  +- org.eclipse.jetty.websocket:websocket-client:jar:9.4.26.v20200117:compile
  |  |  \- org.eclipse.jetty.websocket:websocket-servlet:jar:9.4.26.v20200117:compile

Specifically, javax.websocket-api contains javax.websocket-client-api
plus server classes. Depending on both at once can create version skew.

Author: ctrueden

pom.xml

@@ -3538,6 +3538,13 @@
 				<groupId>org.eclipse.jetty</groupId>
 				<artifactId>jetty-maven-plugin</artifactId>
 				<version>${jetty-maven-plugin.version}</version>
+				<exclusions>
+					<exclusion>
+						<!-- Conflicts with javax.websocket:javax.websocket-api -->
+						<groupId>javax.websocket</groupId>
+						<artifactId>javax.websocket-client-api</artifactId>
+					</exclusion>
+				</exclusions>
 			</dependency>
 			<dependency>
 				<groupId>org.eclipse.jetty</groupId>