private static List<IntermediateOperation> importOperationInputs(Onnx.NodeProto node,
                                                                     Onnx.GraphProto onnxGraph,
                                                                     IntermediateGraph intermediateGraph) {
        return node.getInputList().stream()
                .map(nodeName -> importOperation(nodeName, onnxGraph, intermediateGraph))
                .toList();
    }
Converts an ONNX graph to a Vespa IntermediateGraph which is the basis
for generating Vespa ranking expressions.

@author lesters
model-integration/src/main/java/ai/vespa/rankingexpression/importer/onnx/GraphImporter.java