import com.atlassian.crowd.embedded.api.Group;
import com.atlassian.jira.component.ComponentAccessor;
import com.atlassian.jira.security.groups.GroupManager;
import com.atlassian.jira.user.ApplicationUser;

import java.util.ArrayList;
import java.util.List;

GroupManager groupManager = ComponentAccessor.getGroupManager();

String fromrGroup = "jira-software-users";
String toGroup = "技术部";

List<ApplicationUser> userList = new ArrayList();
userList.addAll(groupManager.getUsersInGroup(fromrGroup));

Group group = groupManager.getGroup(toGroup);
for (int i = 0; i < userList.size(); i++) {
    try {
        groupManager.addUserToGroup(userList.get(i),group);
    } catch (Exception e) {
        e.printStackTrace();
    }
}