mongodb group by connections count on env var

mongodb_group_connections_by_env_var.js

// Assuming "application" is the connection env var to group by connections by.
db.currentOp(true).inprog.reduce(
    (accumulator, connection) => {
        application = connection.clientMetadata && connection.clientMetadata.application ? 
            connection.clientMetadata.application.name : "Internal";    
        accumulator[application] = (accumulator[application] || 0) + 1; 
        accumulator["TOTAL_CONNECTION_COUNT"]++; 
        return accumulator;  
    },  
    { TOTAL_CONNECTION_COUNT: 0 } 
)