code: private String excludeKey(String name, String cmpname, String value) {
          StringBuilder sb = new StringBuilder(cmpname == null ? "" : cmpname + ".");
          sb.append(name).append(value == null ? "" : "=" + value);
          return sb.toString();
      }
docs: Returns the exclusion lookup key for the property.
  
  @param name The property name.
  @param cmpname The component name (may be null).
  @param value The property value (may be null).
  @return The exclusion lookup key.