Complex return type question

[Harry_Wen]

Hi all
I have a method which returns a user-defined compelx object  ..But this
object in turns contains a java.util.Set that contains complex type
elements. Each of the elements again contains complex type objects. I want
to call this method(LogIn) in .NET front end.
How do I deal with this object here? Following are the partial listing of
the involved classes from the parent to the children:

public abstract class Users implements java.io.Serializable {
      protected Set projectRoleColl;

      public Set getProjectRoleColl() {
            return projectRoleColl;
      }

      public void setProjectRoleColl(Set projectRoleColl) {
            this.projectRoleColl = projectRoleColl;
      }
}


public class ProjectRole  implements java.io.Serializable {
      private Role role;
      private Project project;

      public Project getProject() {
            return project;
      }

      public Role getRole() {
            return role;
      }

      public void setProject(Project project) {
            this.project = project;
      }

      public void setRole(Role role) {
            this.role = role;
      }
}


public class Role {

      private Long id;
      private String roleName;
      private Set privilegeColl;

      public Long getId() {
            return id;
      }

      public String getRoleName() {
            return roleName;
      }



      public void setId(Long rid) {
            id = rid;
      }

      public void setRoleName(String  rName) {
            roleName = rName;
      }
      /**
       * Returns the privilegeColl.
       * @return Set
       */
      public Set getPrivilegeColl() {
            return privilegeColl;
      }

      /**
       * Sets the privilegeColl.
       * @param privilegeColl The privilegeColl to set
       */
      public void setPrivilegeColl(Set privilegeColl) {
            this.privilegeColl = privilegeColl;
      }

}



public class Project {

      private Long id;
      private String projectName;
      private Set userColl;

      public Long getId() {
            return id;
      }

      public String getProjectName() {
            return projectName;
      }

      /**
       * Returns the userColl.
       * @return Set
       */
      public Set getUserColl() {
            return userColl;
      }

      public void setId(Long pid) {
            id = pid;
      }

      public void setProjectName(String  pName) {
            projectName = pName;
      }

      /**
       * Sets the userColl.
       * @param userColl The userColl to set
       */
      public void setUserColl(Set userColl) {
            this.userColl = userColl;
      }

}


Here is my C# client code.

Users o = (Users)svc1.LogIn("sandeep-temp", "", "ftis");
ProjectRole obj = (ProjectRole)o.projectRoleColl;

The code in red generates "System.InvalidCastException" with "Additional
information: Specified cast is not valid."  Is there a way to make this
cast valid? Thanks.


Harry Wen