@bajtos I found the command type here a bit confusing: the function types defined at the bottom of this PR only takes string type as command. Any particular reason to allow an object?

the function types defined at the bottom of this PR only takes string type as command.

I forgot to update typedefs, they were describing a callback variant too. I'll fix that.

Any particular reason to allow an object?

Some community connectors are using object value for the comman and I want to preserve support for those connectors.

See e.g. https://www.npmjs.com/package/loopback-connector-neo4j-graph

var cypher = {
    query: "MATCH (u:User {email: {email}}) RETURN u",
    params: {
        email: 'alice@example.com',
    }
};
// ...
ModelClass.dataSource.connector.execute(
    cypher,
    [],
    options,
    callback
);

I think the connector authors misunderstood how command & args are meant to be used together. I think the following would be a better usage:

ModelClass.dataSource.connector.execute(
  `MATCH (u:User {email: {email}}) RETURN u`,
   {email: 'alice@example.com'},
   options,
   callback);

Based on this analysis, I am going to change the type of args from array to object. (Note that arrays are objects too.)