code: public static Map<String, String> getExtensionIconMapping() {
  
          if (m_extensionIconMapping == null) {
              m_extensionIconMapping = new HashMap<String, String>();
              for (Entry<String, String> entry : OpenCms.getResourceManager().getExtensionMapping().entrySet()) {
                  m_extensionIconMapping.put(
                      entry.getKey(),
                      getIconClasses(entry.getValue(), "_." + entry.getKey(), false));
              }
              m_extensionIconMapping.put("", getIconClasses("plain", null, false));
          }
          // returning a copy of the icon map, as GWT will not work with unmodifiable maps
          return new HashMap<String, String>(m_extensionIconMapping);
      }
docs: Returns the extension icon mapping used when uploading files.<p>
  
  @return the extension icon mapping