How to add attachment to an existing JIRA Issue using rest-client API

I could create a jira issue using the rest client API, but i wasn't able to attach the screeshot/attachment to the exsiting JIRA issue. Would be really helpful if anyone could provide a solution which would be really appreciated.

I just wrote the below code snippet for attaching a jpeg file to the existing JIRA Issue. But then i experienced "Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/httpclient/HttpConnectionManager"

Code Snippet :-

private static String addAttachment(String attachmentfilepath) throws URISyntaxException, FileNotFoundException{

    final java.net.URI jiraServerUri = new java.net.URI("https://oliveits.atlassian.net");
    FileInputStream fileStreamPath = new FileInputStream(attachmentfilenamepath);
    JerseyJiraRestClientFactory factory = new JerseyJiraRestClientFactory();
    NullProgressMonitor pm = new NullProgressMonitor();
    System.out.println("Server Url  :"+jiraServerUri);
    JiraRestClient restClient = factory.createWithBasicHttpAuthentication(jiraServerUri,"mobileqa","MobileQA1234");
    Issue issue1 = restClient.getIssueClient().getIssue(newKey, pm);
    final java.net.URI AttachmentUri = new java.net.URI(jiraServerUri+"/rest/api/2/issue/"+newKey+"/attachments");
    System.out.println("URI    :"+issue1.getAttachmentsUri());
    //restClient.getIssueClient().addAttachment(pm,issue1.getAttachmentsUri(), fileStreamPath , imageName);
    restClient.getIssueClient().addAttachment(pm, AttachmentUri, fileStreamPath, imageName);
    return attachmentfilepath;
}

Exception:-

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/httpclient/HttpConnectionManager
at com.atlassian.jira.rest.client.internal.jersey.JerseyJiraRestClientFactory.create(JerseyJiraRestClientFactory.java:34)
at com.atlassian.jira.rest.client.internal.jersey.JerseyJiraRestClientFactory.createWithBasicHttpAuthentication(JerseyJiraRestClientFactory.java:39)
at com.jtricks.JTricksRESTClient.addAttachment(JTricksRESTClient.java:157)
at com.jtricks.JTricksRESTClient.main(JTricksRESTClient.java:101)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.httpclient.HttpConnectionManager
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 4 more

Just added the missing jar files to the classpath. But I'm getting an exception as mentioned below.

Exception Msg-1: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java class com.sun.jersey.multipart.MultiPart, and Java type class com.sun.jersey.multipart.MultiPart, and MIME media type multipart/form-data; boundary=Boundary_1_18541827_1358346116249 was not found

Exception Msg-2: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java class com.sun.jersey.multipart.MultiPart, and Java type class com.sun.jersey.multipart.MultiPart, and MIME media type multipart/form-data; boundary=Boundary_1_18541827_1358346116249 was not found

You issue comes from inability to find org.apache.commons.httpclient.HttpConnectionManager class. Look for commons-httpclient JAR in your classpath.