ClassCastException by using JiraSoapClient inside a JiraPlugin

Hello, I want to use the JiraSoapService in my plugin to communicate with another Jira.
I add this to my pom.xml:

        <dependency>
	       <groupId>com.atlassian.jira.plugins</groupId>
	       <artifactId>jira-soapclient</artifactId>
	       <version>${jira.version}</version>
    	</dependency>

But when I try to login to another Jira.

String baseUrl = url + "/rpc/soap/jirasoapservice-v2";
JiraSoapService jiraSoapService = jiraSoapServiceLocator.getJirasoapserviceV2(new URL(baseUrl));
String login = jiraSoapService.login("admin", "admin");

I get a ClassCastException:

AxisFault
[INFO] [talledLocalContainer] faultCode:

Server.userException
[INFO] [talledLocalContainer] faultSubcode:
[INFO] [talledLocalContainer] faultString: java.lang.ClassCastException: org.apache.axis.attachments.AttachmentsImpl cannot be cast to org.apache.axis.attachments.Attachments
[INFO] [talledLocalContainer] faultActor:
[INFO] [talledLocalContainer] faultNode:
[INFO] [talledLocalContainer] faultDetail:
[INFO] [talledLocalContainer]

stackTrace:java.lang.ClassCastException: org.apache.axis.attachments.AttachmentsImpl cannot be cast to org.apache.axis.attachments.Attachments
[INFO] [talledLocalContainer] at org.apache.axis.Message.setup(Message.java:352)
[INFO] [talledLocalContainer] at org.apache.axis.Message.<init>(Message.java:246)
[INFO] [talledLocalContainer] at org.apache.axis.client.Call.invoke(Call.java:2425)
[INFO] [talledLocalContainer] at org.apache.axis.client.Call.invoke(Call.java:2366)
[INFO] [talledLocalContainer] at org.apache.axis.client.Call.invoke(Call.java:1812)