private static boolean hasInnerStructure(String valueString) {
            valueString = valueString.trim();
            valueString = valueString.substring(1);
            int firstLeftBracket = valueString.indexOf('[');
            return firstLeftBracket >= 0 && firstLeftBracket < valueString.indexOf(']');
        }
Are there inner square brackets in this or is it just a flat list of numbers until ']'?
vespajlib/src/main/java/com/yahoo/tensor/TensorParser.java