Upgrade to newest group manager

Project/Assets/ML-Agents/Examples/Hallway/Scripts/HallwayCollabAgent.cs

 using UnityEngine;
-using Unity.MLAgents.Extensions.MultiAgent;
+using Unity.MLAgents;
 using Unity.MLAgents.Actuators;
 using Unity.MLAgents.Sensors;
 
         base.Initialize();
         if (isSpotter)
         {
-            var teamManager = new BaseMultiAgentGroup();
+            var teamManager = new SimpleMultiAgentGroup();
             teamManager.RegisterAgent(this);
             teamManager.RegisterAgent(teammate);
         }

Project/Assets/ML-Agents/Examples/PushBlock/Scripts/PushBlockEnvController.cs

 using System.Collections;
 using System.Collections.Generic;
-using Unity.MLAgents.Extensions.MultiAgent;
+using Unity.MLAgents;
 using UnityEngine;
 
 public class PushBlockEnvController : MonoBehaviour
 
     private int m_NumberOfRemainingBlocks;
 
-    private BaseMultiAgentGroup m_AgentGroup;
+    private SimpleMultiAgentGroup m_AgentGroup;
 
     private int m_ResetTimer;
 
             item.Rb = item.T.GetComponent<Rigidbody>();
         }
         // Initialize TeamManager
-        m_AgentGroup = new BaseMultiAgentGroup();
+        m_AgentGroup = new SimpleMultiAgentGroup();
         foreach (var item in AgentsList)
         {
             item.StartingPos = item.Agent.transform.position;
         col.gameObject.SetActive(false);
 
         //Give Agent Rewards
-        foreach (var item in AgentsList)
-        {
-            item.Agent.AddReward(score);
-        }
+        m_AgentGroup.AddGroupReward(score);
 
         // Swap ground material for a bit to indicate we scored.
         StartCoroutine(GoalScoredSwapGroundMaterial(m_PushBlockSettings.goalScoredMaterial, 0.5f));

com.unity.ml-agents/Runtime/SimpleMultiAgentGroup.cs

     /// <summary>
     /// A basic class implementation of MultiAgentGroup.
     /// </summary>
-    internal class SimpleMultiAgentGroup : IMultiAgentGroup, IDisposable
+    public class SimpleMultiAgentGroup : IMultiAgentGroup, IDisposable
     {
         readonly int m_Id = MultiAgentGroupIdCounter.GetGroupId();
         HashSet<Agent> m_Agents = new HashSet<Agent>();

com.unity.ml-agents.extensions/Runtime/MultiAgent.meta

-fileFormatVersion: 2
-guid: 77124df6c18c4f669052016b3116147e
-timeCreated: 1610064454