private void assertCurrentTokenIs(JsonToken wantedToken) {
        assertTokenIs(parser.currentToken(), wantedToken);
    }
Tensor labels are always strings. Labels for a mapped dimension can be any string,
but those for indexed dimensions needs to be able to be interpreted as integers, and,
additionally, those for indexed bounded dimensions needs to fall within the dimension size.
config-model/src/main/java/com/yahoo/vespa/model/application/validation/ConstantTensorJsonValidator.java