question: private void findCollapsesFromExistingVertices ( List collapsedVertexIndexes ) { for ( int i = 0 ; i < edge . size ( ) - 2 ; i ++ ) { Coordinate p0 = edge . getCoordinate ( i ) ; Coordinate p1 = edge . getCoordinate ( i + 1 ) ; Coordinate p2 = edge . getCoordinate ( i + 2 ) ; if ( p0 . equals2D ( p2 ) ) { collapsedVertexIndexes . add ( new Integer ( i + 1 ) ) ; } } }
target:  Adds nodes for any collapsed edge pairs which are pre-existing in the vertex list.