code: public boolean hasProperty (@Nonnull final String sProperty)
    {
      ValueEnforcer.notNull (sProperty, "Property");
      return m_sProperty.equals (_unifyProperty (sProperty));
    }
docs: Check if this declaration has the specified property. The comparison is
  case insensitive!
  
  @param sProperty
  The property to check. May not be <code>null</code>.
  @return <code>true</code> if this declaration has the specified property.
  @see #hasProperty(ECSSProperty)
  @since 6.0.0