How to remove duplicate Key-Value pair in Hashmap? - Not only duplicate key or value

I have a hashmap in Java for retreaving APIs of a software system. So, I have something like this:

[SoftwareID, SoftwareAPI]

When I query all APIs for software systems, I get:

[[SoftwareID, SoftwareAPI], [SoftwareID, SoftwareAPI], [SoftwareID, SoftwareAPI]]

But I have a problem, I need to remove all duplicate SoftwareAPIs for each software.

For example, when I iterate over my hash file, I get

[ [0, A], [0, B], [0, A], [0, A] ];

[ [1, A], [1, B], [1, B], [1, C] ];

[ [2, A], [2, B], [2, A] ];

      

        
        
        
      

    

but I need to remove duplicate pairs, so it would be something like this:

[ [0, A], [0, B] ];

[ [1, A], [1, B], [1, C] ];

[ [2, A], [2, B] ]

      

        
        
        
      

    

Just to add some information about the codes, this is a piece of code:

// HashMap APIs per user/Systems
HashMap<Integer, Set<API>> apisPerSystem = new HashMap<Integer, Set<API>>();

/**
 * Stores a API in the data model
 * @param system the user
 * @param api the item
 * @return the newly added API
 */
public API addAPIs(int system, String api) {
    API r = new API(system,api);
    apis.add(r);
    Set<API> systemApis = apisPerUser.get(system);
    if (systemApis == null) {
        systemApis = new HashSet<API>();
    }
    apisPerUser.put(system, systemApis);
    systemApis.add(r);
    systems.add(system);
    apisList.add(api);
    return r;
}

// Get the APIs per Systemfrom the outside.
public HashMap<Integer, Set<API>> getAPIsPerSystem() {
    return apisPerSystem;
}