Image buffer inside a vxImage not guaranteed to exist before vxVerifyGraph()

the spec says (page 224) that the image buffer is not guaranteed to exist until the vx_graph containing it has been verified. Yet in the the conformance test code (eg test_sobel3x3.c) I see
that ct_image_to_vx_image() will create a vx_image and then writes into it, before the vxVerifyGraph() is called a few lines later. Is this a violation of the spec? Am I missing something?

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ASSERT_NO_FAILURE(src = arg_->generator(arg_->fileName, arg_->width, arg_->height));

ASSERT_VX_OBJECT(src_image = ct_image_to_vx_image(src, context), VX_TYPE_IMAGE);

dst_x_image = ct_create_similar_image_with_format(src_image, VX_DF_IMAGE_S16);
ASSERT_VX_OBJECT(dst_x_image, VX_TYPE_IMAGE);

dst_y_image = ct_create_similar_image_with_format(src_image, VX_DF_IMAGE_S16);
ASSERT_VX_OBJECT(dst_y_image, VX_TYPE_IMAGE);

graph = vxCreateGraph(context);
ASSERT_VX_OBJECT(graph, VX_TYPE_GRAPH);

node = vxSobel3x3Node(graph, src_image, dst_x_image, dst_y_image);
ASSERT_VX_OBJECT(node, VX_TYPE_NODE);

VX_CALL(vxSetNodeAttribute(node, VX_NODE_BORDER, &border, sizeof(border)));

VX_CALL(vxVerifyGraph(graph));
VX_CALL(vxProcessGraph(graph));

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