private static TensorType readProbedOutputType(ApplicationPackage app, Path modelPath,
                                                   String contextKey) throws IOException {
        ApplicationFile file = app.getFile(probedOutputTypesPath(modelPath));
        if ( ! file.exists()) {
            return TensorType.empty;
        }
        try (BufferedReader reader = new BufferedReader(file.createReader())) {
            String line;
            while (null != (line = reader.readLine())) {
                String[] parts = line.split("\t");
                String key = parts[0];
                if (key.equals(contextKey)) {
                    return TensorType.fromSpec(parts[1]);
                }
            }
        }
        return TensorType.empty;
    }
Defers to 'vespa-analyze-onnx-model' to determine the output type given
a set of inputs. For situations with symbolic dimension sizes that can't
easily be determined.

@author lesters
config-model/src/main/java/com/yahoo/vespa/model/ml/OnnxModelProbe.java