private static TensorType typeFromMappedValueString(String valueString) {
        TensorType.Builder builder = new TensorType.Builder();
        MappedValueTypeParser parser = new MappedValueTypeParser(valueString, builder);
        parser.parse();
        return builder.build();
    }
Derives the tensor type from the first address string in the given tensor string
vespajlib/src/main/java/com/yahoo/tensor/TensorParser.java