graphdb/src/main/java/com/tinkerpop/blueprints/impls/orient/OrientEdge.java
@Override
  public void setProperty(final String key, final Object value) {
    setCurrentGraphInThreadLocal();

    if (rawElement == null)
      // LIGHTWEIGHT EDGE
      convertToDocument();

    super.setProperty(key, value);
  }
@Override
  public void setProperty(final String key, final Object value) {
    setCurrentGraphInThreadLocal();

    if (rawElement == null)
      // LIGHTWEIGHT EDGE
      convertToDocument();

    super.setProperty(key, value);
  }
Set a Property value. If the edge is lightweight, it's transparently transformed into a regular edge.

@param key   Property name
@param value Property value