Engine API not working with Bonita docker container (v7.8.3)

Hello,

I'm trying to write some Java script that uses Bonita engine API to interact with a Bonita docker container. The docker-compose file and the Java code are as follows.

docker-compose.yml: (followed instructions on https://hub.docker.com/_/bonita)

# Use tech_user/secret as user/password credentials
version: "3"

services:
  # Database
  db:
    image: postgres:9.3
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=example
    command:
      - -c
      - max_connections=300
      - -c
      - max_prepared_transactions=300
    ports:
      - 5050:5432

# Bonita
bonita:
    image: bonita:7.8.3
        ports:
          - 8080:8080
        environment:
          - POSTGRES_ENV_POSTGRES_PASSWORD=example
          - DB_VENDOR=postgres
          - DB_HOST=db
          - TENANT_LOGIN=tech_user
          - TENANT_PASSWORD=secret
          - PLATFORM_LOGIN=pfadmin
          - PLATFORM_PASSWORD=pfsecret
          - HTTP_API=true
          - REST_API_DYN_AUTH_CHECKS=false
        depends_on:
          - db
        entrypoint:
          - bash
          - -c
          - |
            set -e
            echo 'Waiting for Postgres to be available'
            export PGPASSWORD="$$POSTGRES_ENV_POSTGRES_PASSWORD"
            maxTries=10
            while [ "$$maxTries" -gt 0 ] && ! psql -h "$$DB_HOST" -U 'postgres' -c '\l'; do
                let maxTries--
                sleep 1
            done
            echo
            if [ "$$maxTries" -le 0 ]; then
                echo >&2 'error: unable to contact Postgres after 10 tries'
                exit 1
            fi
            exec /opt/files/startup.sh

Java code: (followed instructions on https://documentation.bonitasoft.com/bonita/7.8/configure-client-of-boni...)

package com.mycompany.app;

import java.util.HashMap;
import java.util.Map;

import org.bonitasoft.engine.api.ApiAccessType;
import org.bonitasoft.engine.api.LoginAPI;
import org.bonitasoft.engine.api.TenantAPIAccessor;
import org.bonitasoft.engine.api.TenantAdministrationAPI;
import org.bonitasoft.engine.exception.BonitaHomeNotSetException;
import org.bonitasoft.engine.exception.ServerAPIException;
import org.bonitasoft.engine.exception.UnknownAPITypeException;
import org.bonitasoft.engine.platform.LoginException;
import org.bonitasoft.engine.session.APISession;
import org.bonitasoft.engine.util.APITypeManager;

public class App {

    public static void main(String[] args) {

        final String host = "http://localhost:8080";
        // final String host = "http://localhost:1760";
        final String username = "tech_user";
        // final String username = "install";
        final String password = "secret";
        // final String password = "install";

        Map<String, String> settings = new HashMap<String, String>();
        settings.put("server.url", host);
        settings.put("application.name", "bonita");
        APITypeManager.setAPITypeAndParams(ApiAccessType.HTTP, settings);

        // get the LoginAPI using the TenantAPIAccessor
        try {
            LoginAPI loginAPI = TenantAPIAccessor.getLoginAPI();
            // log in to the tenant to create a session
            APISession apiSession = loginAPI.login(username, password);
            System.out.println(apiSession.getUserName());
            System.out.println(apiSession.isTechnicalUser());

            TenantAdministrationAPI tenantApi = TenantAPIAccessor.getTenantAdministrationAPI(apiSession);

            // System.out.println(tenantApi.isPaused() ? "Paused" : "Running");
            // tenantApi.pause();
            // System.out.println(tenantApi.isPaused() ? "Paused" : "Running");
            // tenantApi.resume();
            // System.out.println(tenantApi.isPaused() ? "Paused" : "Running");
        } catch (LoginException e) {
            e.printStackTrace();
        } catch (BonitaHomeNotSetException e) {
            e.printStackTrace();
        } catch (ServerAPIException e) {
            e.printStackTrace();
        } catch (UnknownAPITypeException e) {
            e.printStackTrace();
        }

    }
}

PROBLEM
The script works for the Bonita Studio's embedded server (hosted at localhost:1760). Logging in as "install" user, pausing and unpausing BPM service work successfully (commented out code).
However, when I change the connection to Bonita docker service (hosted at localhost:8080), the following error is shown while the script tries to login:

Exception in thread "main" java.lang.reflect.UndeclaredThrowableException
at com.sun.proxy.$Proxy0.login(Unknown Source)
    at com.mycompany.app.App.main(App.java:42)
App.java:42
Caused by: java.io.IOException: Error while executing POST request (http code: 404) <POST http://localhost:8080/bonita/serverAPI/org.bonitasoft.engine.api.LoginAPI/login HTTP/1.1>
    at org.bonitasoft.engine.api.HTTPServerAPI.invokeMethod(HTTPServerAPI.java:128)
HTTPServerAPI.java:128
    at org.bonitasoft.engine.api.impl.ClientInterceptor.invoke(ClientInterceptor.java:86)
ClientInterceptor.java:86
    at com.sun.proxy.$Proxy0.login(Unknown Source)
    at com.mycompany.app.App.main(App.java:42)
App.java:42
    at  < ========== Beginning of the server stack trace ========== >. ( )
    at org.bonitasoft.engine.api.HTTPServerAPI.executeHttpPost(HTTPServerAPI.java:160)
HTTPServerAPI.java:160
    at org.bonitasoft.engine.api.HTTPServerAPI.invokeMethod(HTTPServerAPI.java:123)
HTTPServerAPI.java:123
    at org.bonitasoft.engine.api.impl.ClientInterceptor.invoke(ClientInterceptor.java:86)
ClientInterceptor.java:86
    ... 2 more
Caused by: org.apache.http.client.HttpResponseException: 
    at org.apache.http.impl.client.AbstractResponseHandler.handleResponse(AbstractResponseHandler.java:69)
AbstractResponseHandler.java:69
    at org.apache.http.impl.client.BasicResponseHandler.handleResponse(BasicResponseHandler.java:65)
BasicResponseHandler.java:65
    at org.apache.http.impl.client.BasicResponseHandler.handleResponse(BasicResponseHandler.java:51)
BasicResponseHandler.java:51
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:222)
CloseableHttpClient.java:222
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:164)
CloseableHttpClient.java:164
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:139)
CloseableHttpClient.java:139
    at org.bonitasoft.engine.api.HTTPServerAPI.executeHttpPost(HTTPServerAPI.java:152)
HTTPServerAPI.java:152
    ... 4 more

QUESTION
HOW TO MAKE THE LOGIN API CALL IN ABOVE JAVA CODE TO RUN SUCCESSFULLY WITH THE DOCKER CONTAINER? (the one at localhost:8080) AM I MISSING SOME CONFIGURATION?

APISession apiSession = loginAPI.login(username, password); // Failing

SUSPICION
I suspect that Bonita docker image did not configure the class path correctly, so that the loginAPI implementation was not found.

Anyway, can some professional lend a helping hand?

Docker

engine api