graphdb/src/main/java/com/orientechnologies/orient/graph/batch/OGraphBatchInsertBasic.java
public void createEdge(final Long from, final Long to) {
    if (from < 0) {
      throw new IllegalArgumentException(" Invalid vertex id: " + from);
    }
    if (to < 0) {
      throw new IllegalArgumentException(" Invalid vertex id: " + to);
    }
    last = last < from ? from : last;
    last = last < to ? to : last;
    putInList(from, out, to);
    putInList(to, in, from);
  }
public void createEdge(final Long from, final Long to) {
    if (from < 0) {
      throw new IllegalArgumentException(" Invalid vertex id: " + from);
    }
    if (to < 0) {
      throw new IllegalArgumentException(" Invalid vertex id: " + to);
    }
    last = last < from ? from : last;
    last = last < to ? to : last;
    putInList(from, out, to);
    putInList(to, in, from);
  }
Creates a new edge between two vertices. If vertices do not exist, they will be created

@param from
id of the vertex that is starting point of the edge
@param to
id of the vertex that is end point of the edge