Connection to Jira with jdk version 1.5

[Joachim H.]

I try to make a connection to Jira

My Code:
....
JiraRestClientFactory restClientFactory = new AsynchronousJiraRestClientFactory();
JiraRestClient restClient = restClientFactory.createWithBasicHttpAuthentication(uri, user, password);
....

I have the following error:

exception
javax.servlet.ServletException: Servlet execution threw an exception
...
root cause
java.lang.UnsupportedClassVersionError: Bad version number in .class file (unable to load class com.atlassian.jira.rest.client.api.JiraRestClientFactory)
...

I use these libs (and the needed dependencies):
jira-rest-java-client-api-2.0.0-m25.jar
jira-rest--java-client-core-2.0.0-m25.jar

I use in my project the jdk version 1.5. What is the required jdk version for the class 'AsynchronousJiraRestClientFactory()'?
Exists a other possibility to connect with Jira (with jdk 1.5)? I use the class 'AsynchronousJiraRestClientFactory()', because the class 'JerseyJiraRestClientFactory' ist not included (tutorial).

[Pedro Cora]

Currently the most recent versions of JIRA will run on JDK 1.6 and 1.7. 1.5 is no longer used, neither supported for a while already.