diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/runtime/services/context/mocks/MySpace.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/runtime/services/context/mocks/MySpace.sarl
index a31532ddbc..fe40e155f8 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/runtime/services/context/mocks/MySpace.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/runtime/services/context/mocks/MySpace.sarl
@@ -42,14 +42,21 @@ class MySpace implements Space {
 	override getSpaceID : SpaceID {
 		this.id
 	}
-	
+
 	def forEachStrongParticipant(callback : (UUID)=>void) {
 	}
-	
+
 	def getNumberOfStrongParticipants : int {
 		0
 	}
-	
+
+	def forEachWeakParticipant(callback : (UUID)=>void) {
+	}
+
+	def getNumberOfWeakParticipants : int {
+		0
+	}
+
 	def isPseudoEmpty(id : UUID) : boolean {
 		true
 	}
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/internal/AgentPlatformEventEmitterTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/internal/AgentPlatformEventEmitterTest.sarl
index be99b2bbf8..0b79fc4dd6 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/internal/AgentPlatformEventEmitterTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/internal/AgentPlatformEventEmitterTest.sarl
@@ -39,6 +39,7 @@ import io.sarl.tests.api.Nullable
 import io.sarl.tests.api.extensions.ContextInitExtension
 import io.sarl.tests.api.extensions.JavaVersionCheckExtension
 import java.util.UUID
+import java.util.concurrent.ConcurrentLinkedDeque
 import java.util.logging.Logger
 import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.DisplayName
@@ -157,7 +158,7 @@ class AgentEventEmitterTest {
 		when(ctx.ID).thenReturn(secondContext)
 		var ref2 = this.life2.addExternalContext(ctx, adr2)
 		
-		var contexts = #[ref1, ref2]
+		var contexts = new ConcurrentLinkedDeque(#[ref1, ref2])
 		
 		this.emitter.agentDestroyed(agent2, contexts)
 
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/AbstractLifecycleServiceTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/AbstractLifecycleServiceTest.sarl
index f20f13d40b..0bf10984d8 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/AbstractLifecycleServiceTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/AbstractLifecycleServiceTest.sarl
@@ -56,6 +56,7 @@ import io.sarl.tests.api.extensions.JavaVersionCheckExtension
 import java.util.ArrayList
 import java.util.List
 import java.util.UUID
+import java.util.concurrent.ConcurrentLinkedDeque
 import java.util.concurrent.Future
 import java.util.logging.Logger
 import javax.inject.Provider
@@ -148,7 +149,7 @@ abstract class AbstractLifecycleServiceTest<T extends AbstractLifecycleService>
 		when(agentProvider.apply(any)).thenReturn(this.^agent2)
 		this.agentCreatorProvider = typeof(AgentCreatorProvider).mock
 		when(this.agentCreatorProvider.getAgentCreator(typeof(Class).any,
-			typeof(UUID).any, anyInt, typeof(Iterable).any)).thenReturn(agentProvider)
+			typeof(UUID).any, anyInt, typeof(ConcurrentLinkedDeque).any)).thenReturn(agentProvider)
 
 		this.executor = typeof(ExecutorService).mock
 		// Execute the code synchronously only for testing purpose
@@ -404,7 +405,8 @@ abstract class AbstractLifecycleServiceTest<T extends AbstractLifecycleService>
 		
 		// Agent destroy notification
 		capAgent = ArgumentCaptor::forClass(typeof(Agent))
-		var capContexts : ArgumentCaptor<Iterable<ContextReference>> = ArgumentCaptor::forClass(typeof(Iterable))
+		var capContexts : ArgumentCaptor<ConcurrentLinkedDeque<ContextReference>> = ArgumentCaptor::forClass(
+			typeof(ConcurrentLinkedDeque))
 		listener1.verify.agentDestroyed(capAgent.capture, capContexts.capture)
 		this.agent2.assertEquals(capAgent.value)
 		capContexts.value.map[it.getContext].assertContains(defaultContext, outerContext)
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/XAbstractCreatorFactoryTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/XAbstractCreatorFactoryTest.sarl
index b06638f4dc..452fc0d233 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/XAbstractCreatorFactoryTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/XAbstractCreatorFactoryTest.sarl
@@ -29,6 +29,7 @@ import io.sarl.sre.tests.units.services.lifecycle.mocks.MyCap
 import io.sarl.sre.tests.units.services.lifecycle.mocks.XAbstractCreatorFactoryMock
 import io.sarl.tests.api.extensions.ContextInitExtension
 import io.sarl.tests.api.extensions.JavaVersionCheckExtension
+import java.util.concurrent.ConcurrentLinkedDeque
 import org.junit.jupiter.api.DisplayName
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.^extension.ExtendWith
@@ -64,7 +65,7 @@ class XAbstractCreatorFactoryTest {
 	def mergeSkillProviders_0_emptyIterable : void {
 		var factory = new XAbstractCreatorFactoryMock
 		//
-		var provider = factory.mergeSkillProviders(emptyList)
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque)
 		//
 		provider.assertNull
 	}
@@ -75,7 +76,7 @@ class XAbstractCreatorFactoryTest {
 		var factory = new XAbstractCreatorFactoryMock
 		//
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
-		var provider = factory.mergeSkillProviders(#[subprovider0])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0]))
 		//
 		provider.assertNotNull
 		//
@@ -91,7 +92,7 @@ class XAbstractCreatorFactoryTest {
 		//
 		val expected0 = typeof(Skill).mock
 		var subprovider0 = new Provider(expected0)
-		var provider = factory.mergeSkillProviders(#[subprovider0])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0]))
 		//
 		provider.assertNotNull
 		//
@@ -109,7 +110,7 @@ class XAbstractCreatorFactoryTest {
 		var subprovider0 = new Provider(expected0)
 		val expected1 = typeof(Skill).mock
 		var subprovider1 = new Provider(expected1)
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -126,7 +127,7 @@ class XAbstractCreatorFactoryTest {
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
 		val expected1 = typeof(Skill).mock
 		var subprovider1 = new Provider(expected1)
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -142,7 +143,7 @@ class XAbstractCreatorFactoryTest {
 		//
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
 		var subprovider1 = DynamicSkillProvider::EMPTY_PROVIDER
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -172,7 +173,7 @@ class XAbstractCreatorFactoryTest {
 		var orig = DynamicSkillProvider::EMPTY_PROVIDER
 		var factory = new XAbstractCreatorFactoryMock(orig)
 		//
-		var provider = factory.mergeSkillProviders(emptyList)
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque)
 		//
 		var s = provider.createSkill(typeof(MyCap))
 		//
@@ -186,7 +187,7 @@ class XAbstractCreatorFactoryTest {
 		var factory = new XAbstractCreatorFactoryMock(orig)
 		//
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
-		var provider = factory.mergeSkillProviders(#[subprovider0])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0]))
 		//
 		provider.assertNotNull
 		//
@@ -203,7 +204,7 @@ class XAbstractCreatorFactoryTest {
 		//
 		val expected0 = typeof(Skill).mock
 		var subprovider0 = new Provider(expected0)
-		var provider = factory.mergeSkillProviders(#[subprovider0])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0]))
 		//
 		provider.assertNotNull
 		//
@@ -222,7 +223,7 @@ class XAbstractCreatorFactoryTest {
 		var subprovider0 = new Provider(expected0)
 		val expected1 = typeof(Skill).mock
 		var subprovider1 = new Provider(expected1)
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -240,7 +241,7 @@ class XAbstractCreatorFactoryTest {
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
 		val expected1 = typeof(Skill).mock
 		var subprovider1 = new Provider(expected1)
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -257,7 +258,7 @@ class XAbstractCreatorFactoryTest {
 		//
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
 		var subprovider1 = DynamicSkillProvider::EMPTY_PROVIDER
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -289,7 +290,7 @@ class XAbstractCreatorFactoryTest {
 		var orig = new Provider(expected)
 		var factory = new XAbstractCreatorFactoryMock(orig)
 		//
-		var provider = factory.mergeSkillProviders(emptyList)
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque)
 		//
 		provider.assertNotNull
 		//
@@ -306,7 +307,7 @@ class XAbstractCreatorFactoryTest {
 		var factory = new XAbstractCreatorFactoryMock(orig)
 		//
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
-		var provider = factory.mergeSkillProviders(#[subprovider0])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0]))
 		//
 		provider.assertNotNull
 		//
@@ -324,7 +325,7 @@ class XAbstractCreatorFactoryTest {
 		//
 		val expected0 = typeof(Skill).mock
 		var subprovider0 = new Provider(expected0)
-		var provider = factory.mergeSkillProviders(#[subprovider0])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0]))
 		//
 		provider.assertNotNull
 		//
@@ -344,7 +345,7 @@ class XAbstractCreatorFactoryTest {
 		var subprovider0 = new Provider(expected0)
 		val expected1 = typeof(Skill).mock
 		var subprovider1 = new Provider(expected1)
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -363,7 +364,7 @@ class XAbstractCreatorFactoryTest {
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
 		val expected1 = typeof(Skill).mock
 		var subprovider1 = new Provider(expected1)
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
@@ -381,7 +382,7 @@ class XAbstractCreatorFactoryTest {
 		//
 		var subprovider0 = DynamicSkillProvider::EMPTY_PROVIDER
 		var subprovider1 = DynamicSkillProvider::EMPTY_PROVIDER
-		var provider = factory.mergeSkillProviders(#[subprovider0, subprovider1])
+		var provider = factory.mergeSkillProviders(new ConcurrentLinkedDeque(#[subprovider0, subprovider1]))
 		//
 		provider.assertNotNull
 		//
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MyEventBus.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MyEventBus.sarl
index 190eec1131..71ab317e3a 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MyEventBus.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MyEventBus.sarl
@@ -44,11 +44,13 @@ skill MyEventBus implements InternalEventBusCapacity {
 	override unregisterEventBusListener(type : Class<?>, callback : (Object)=>boolean) {
 	}
 
-	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean) : Iterable<Event> {
+	override fireEventAndWait(^event : Event, gatherEvents : boolean,
+		thrownExceptions : boolean) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
-	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean, listener : Object) : Iterable<Event> {
+	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean,
+		listener : Object) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MySkill.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MySkill.sarl
index a0f45c130f..8eb093d1f7 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MySkill.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/MySkill.sarl
@@ -52,16 +52,17 @@ skill MySkill implements InternalEventBusCapacity {
 	}
 
 	@SuppressWarnings("potential_field_synchronization_problem")
-	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean) : Iterable<Event> {
+	override fireEventAndWait(^event : Event, gatherEvents : boolean,
+		thrownExceptions : boolean) : ConcurrentLinkedDeque<Event> {
 		if (this.failure) {
 			throw new RuntimeException
 		}
-		emptyList
+		new ConcurrentLinkedDeque
 	}
 
 	@SuppressWarnings("potential_field_synchronization_problem")
 	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean,
-		listener : Object) : Iterable<Event> {
+		listener : Object) : ConcurrentLinkedDeque<Event> {
 		if (this.failure) {
 			throw new RuntimeException
 		}
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/XAbstractCreatorFactoryMock.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/XAbstractCreatorFactoryMock.sarl
index 812108db05..7a54156574 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/XAbstractCreatorFactoryMock.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/lifecycle/mocks/XAbstractCreatorFactoryMock.sarl
@@ -25,6 +25,7 @@ import io.sarl.lang.core.Agent
 import io.sarl.lang.core.DynamicSkillProvider
 import io.sarl.sre.services.lifecycle.AbstractCreatorFactory
 import java.util.UUID
+import java.util.concurrent.ConcurrentLinkedDeque
 
 /**
  * @author $Author: sgalland$
@@ -36,7 +37,7 @@ import java.util.UUID
 class XAbstractCreatorFactoryMock extends AbstractCreatorFactory {
 	
 	def getAgentCreator(agentClazz : Class<? extends Agent>, parent : UUID, nbAgents : int,
-		skillProviders : Iterable<DynamicSkillProvider>) : (UUID)=>Agent {
+		skillProviders : ConcurrentLinkedDeque<DynamicSkillProvider>) : (UUID)=>Agent {
 		null
 	}
 	
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/AgentNamespaceFinderTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/AgentNamespaceFinderTest.sarl
index 5e1355cb0a..0f2046019b 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/AgentNamespaceFinderTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/AgentNamespaceFinderTest.sarl
@@ -111,8 +111,6 @@ class AgentNamespaceServiceTest {
 		map0b.put(UUID::randomUUID, typeof(Participant).mock)
 		map0b.put(UUID::randomUUID, typeof(Participant).mock)
 		var spc0 = typeof(MySpace).mock
-		when(spc0.internalStrongParticipantStructure).thenReturn(map0)
-		when(spc0.internalWeakParticipantStructure).thenReturn(map0b)
 		var ctx0 = typeof(Context).mock
 		when(ctx0.defaultSpace).thenReturn(spc0)
 
@@ -130,8 +128,6 @@ class AgentNamespaceServiceTest {
 		map1b.put(UUID::randomUUID, typeof(Participant).mock)
 		this.sid1 = UUID::randomUUID
 		var spc1 = typeof(MySpace).mock
-		when(spc1.internalStrongParticipantStructure).thenReturn(map1)
-		when(spc1.internalWeakParticipantStructure).thenReturn(map1b)
 		this.cid1 = UUID::randomUUID
 		var ctx1 = typeof(Context).mock
 		when(ctx1.getSpace(any(typeof(UUID)))).thenAnswer [
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/BehaviorNamespaceFinderTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/BehaviorNamespaceFinderTest.sarl
index 9bef4d5160..694693a015 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/BehaviorNamespaceFinderTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/BehaviorNamespaceFinderTest.sarl
@@ -136,8 +136,6 @@ class BehaviorNamespaceFinderTest {
 		map0b.put(UUID::randomUUID, typeof(Participant).mock)
 		map0b.put(UUID::randomUUID, typeof(Participant).mock)
 		var spc0 = typeof(MySpace).mock
-		when(spc0.internalStrongParticipantStructure).thenReturn(map0)
-		when(spc0.internalWeakParticipantStructure).thenReturn(map0b)
 		var ctx0 = typeof(Context).mock
 		when(ctx0.defaultSpace).thenReturn(spc0)
 
@@ -159,8 +157,6 @@ class BehaviorNamespaceFinderTest {
 		map1b.put(UUID::randomUUID, typeof(Participant).mock)
 		this.sid1 = UUID::randomUUID
 		var spc1 = typeof(MySpace).mock
-		when(spc1.internalStrongParticipantStructure).thenReturn(map1)
-		when(spc1.internalWeakParticipantStructure).thenReturn(map1b)
 		this.cid1 = UUID::randomUUID
 		var ctx1 = typeof(Context).mock
 		when(ctx1.getSpace(any(typeof(UUID)))).thenAnswer [
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/SkillNamespaceFinderTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/SkillNamespaceFinderTest.sarl
index 4c940fbe11..fc1a4ab54a 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/SkillNamespaceFinderTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/services/namespace/SkillNamespaceFinderTest.sarl
@@ -117,12 +117,7 @@ class SkillNamespaceFinderTest {
 		when(participant0.participant).thenReturn(listener0)
 		var map0 = new ConcurrentHashMap
 		map0.put(this.aid0, participant0)
-		var map0b = new ConcurrentHashMap
-		map0b.put(UUID::randomUUID, typeof(Participant).mock)
-		map0b.put(UUID::randomUUID, typeof(Participant).mock)
 		var spc0 = typeof(MySpace).mock
-		when(spc0.internalStrongParticipantStructure).thenReturn(map0)
-		when(spc0.internalWeakParticipantStructure).thenReturn(map0)
 		var ctx0 = typeof(Context).mock
 		when(ctx0.defaultSpace).thenReturn(spc0)
 
@@ -141,8 +136,6 @@ class SkillNamespaceFinderTest {
 		map1b.put(UUID::randomUUID, typeof(Participant).mock)
 		this.sid1 = UUID::randomUUID
 		var spc1 = typeof(MySpace).mock
-		when(spc1.internalStrongParticipantStructure).thenReturn(map1)
-		when(spc1.internalWeakParticipantStructure).thenReturn(map1b)
 		this.cid1 = UUID::randomUUID
 		var ctx1 = typeof(Context).mock
 		when(ctx1.getSpace(any(typeof(UUID)))).thenAnswer [
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill.sarl
index e16d185c03..2f3e862800 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill.sarl
@@ -60,12 +60,13 @@ skill MyInternalEventBusSkill implements InternalEventBusCapacity {
 	override unregisterEventBusListener(type : Class<?>, callback : (Object)=>boolean) {
 	}
 
-	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean) : Iterable<Event> {
+	override fireEventAndWait(^event : Event, gatherEvents : boolean,
+		thrownExceptions : boolean) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
 	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean,
-	listener : Object) : Iterable<Event> {
+	listener : Object) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill2.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill2.sarl
index ea208cca64..a463fbc9a5 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill2.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MyInternalEventBusSkill2.sarl
@@ -49,12 +49,13 @@ skill MyInternalEventBusSkill2 implements InternalEventBusCapacity {
 	override unregisterEventBusListener(type : Class<?>, callback : (Object)=>boolean) {
 	}
 
-	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean) : Iterable<Event> {
+	override fireEventAndWait(^event : Event, gatherEvents : boolean,
+		thrownExceptions : boolean) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
 	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean,
-				listener : Object) : Iterable<Event> {
+				listener : Object) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MySkill.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MySkill.sarl
index caba5438bf..5b323288dd 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MySkill.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/skills/bic/mocks/MySkill.sarl
@@ -46,12 +46,13 @@ skill MySkill implements InternalEventBusCapacity {
 	override unregisterEventBusListener(type : Class<?>, callback : (Object)=>boolean) {
 	}
 
-	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean) : Iterable<Event> {
+	override fireEventAndWait(^event : Event, gatherEvents : boolean,
+		thrownExceptions : boolean) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
 	override fireEventAndWait(^event : Event, gatherEvents : boolean, thrownExceptions : boolean,
-		listener : Object) : Iterable<Event> {
+		listener : Object) : ConcurrentLinkedDeque<Event> {
 		null
 	}
 
diff --git a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/spaces/XAbstractSpaceTest.sarl b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/spaces/XAbstractSpaceTest.sarl
index 9f979e5e5c..c829e9b6f9 100644
--- a/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/spaces/XAbstractSpaceTest.sarl
+++ b/sre/io.janusproject/io.janusproject.tests/src/test/sarl/io/sarl/sre/tests/units/spaces/XAbstractSpaceTest.sarl
@@ -60,6 +60,12 @@ class XAbstractSpaceTest {
 			def getNumberOfStrongParticipants : int {
 				throw new UnsupportedOperationException
 			}
+			def forEachWeakParticipant(callback : (UUID)=>void) {
+				throw new UnsupportedOperationException
+			}
+			def getNumberOfWeakParticipants : int {
+				throw new UnsupportedOperationException
+			}
 			def isPseudoEmpty(id : UUID) : boolean {
 				throw new UnsupportedOperationException
 			}