code: @Override
      public String findProperty( final String propertyName )
      {
          String value = m_bundleContext.getProperty( propertyName );
          if( value != null && value.trim().length() == 0 )
          {
              value = null;
          }
          return value;
      }
docs: Resolves a property based on it's name by:<br>
  1. if there is a configuration available look for the property;<br>
  2. if property is not set or there is no configuration available look for a framework / system property.
  
  @param propertyName property name to be resolved
  @return value of property or null if property is not set or is empty.