AEM 6.1 Touch UI | Populating Drop Down | Fetching resourceType of the actual component in datasource

""But when I do "resource.getResourceType()" 

I do not think this is necessary at all. You can invoke a OSGi service and populate a DataSource object without using getReourceType. Then the TouchUI dropdown will be populated with data. 

For example - assume you want to read a specific resource in the JCR (a node somewhere) and create a map using its node props (rest of this answer addresses this use case)  

If you want to populate a Map with JCR data - write a method in the OSGi bundle that performs these tasks:

1-  gets node data (from a specific node in the JCR)

2 - populates a map using the data

3 - returns the map.

For example - OSGi service that returns a map:

public HashMap getMapData(String url)
  {
    try
    {
      this.resourcePath = url;
      ResourceResolver resourceResolver = this.resolverFactory
        .getAdministrativeResourceResolver(null);
      Resource res = resourceResolver.getResource(this.resourcePath);
      ValueMap readMap = res.getValueMap();
      HashMap<String, String> myMap= new HashMap();

//populate the map

return myMap; 

} 

In your JSP - you can call this method

optionMap = mySource.getMapData(pathFieldValue);

If you need a JCR Path to point to the node - then use a PathField in the dialog of the component. Get the value of the pathfield in the JSP and pass that to getMapData (apthFieldValue argument).

For example:

Then the Java code can read that and populate the map with the JCR node prop name and values. (shown above).

THen the drop-down in the TOuch UI will then display node props names and prop values.