Refactor get_attesting_indices (#8090)

* refactor get_attesting_indices (Electra phase0 changes)

acceptance-tests/src/testFixtures/java/tech/pegasys/teku/test/acceptance/dsl/TekuBeaconNode.java

@@ -693,12 +693,7 @@ public void waitForAttestationBeingGossiped(
 
           Set<UInt64> attesterIndicesInAttestations =
               block.getMessage().getBody().attestations.stream()
-                  .map(
-                      a ->
-                          spec.getAttestingIndices(
-                              state,
-                              a.asInternalAttestation(spec).getData(),
-                              a.asInternalAttestation(spec).getAggregationBits()))
+                  .map(a -> spec.getAttestingIndices(state, a.asInternalAttestation(spec)))
                   .flatMap(Collection::stream)
                   .map(UInt64::valueOf)
                   .collect(toSet());

ethereum/spec/src/main/java/tech/pegasys/teku/spec/Spec.java

@@ -42,7 +42,6 @@
 import tech.pegasys.teku.infrastructure.bytes.Bytes4;
 import tech.pegasys.teku.infrastructure.ssz.Merkleizable;
 import tech.pegasys.teku.infrastructure.ssz.SszList;
-import tech.pegasys.teku.infrastructure.ssz.collections.SszBitlist;
 import tech.pegasys.teku.infrastructure.unsigned.UInt64;
 import tech.pegasys.teku.spec.cache.IndexedAttestationCache;
 import tech.pegasys.teku.spec.config.NetworkingSpecConfig;
@@ -868,8 +867,8 @@ public Map<Integer, CommitteeAssignment> getValidatorIndexToCommitteeAssignmentM
   }
 
   // Attestation helpers
-  public IntList getAttestingIndices(BeaconState state, AttestationData data, SszBitlist bits) {
-    return atState(state).getAttestationUtil().getAttestingIndices(state, data, bits);
+  public IntList getAttestingIndices(final BeaconState state, final Attestation attestation) {
+    return atState(state).getAttestationUtil().getAttestingIndices(state, attestation);
   }
 
   public AttestationData getGenericAttestationData(

ethereum/spec/src/main/java/tech/pegasys/teku/spec/datastructures/operations/Attestation.java

@@ -28,8 +28,8 @@
 import tech.pegasys.teku.spec.datastructures.type.SszSignature;
 import tech.pegasys.teku.spec.datastructures.type.SszSignatureSchema;
 
-public class Attestation
-    extends Container3<Attestation, SszBitlist, AttestationData, SszSignature> {
+public class Attestation extends Container3<Attestation, SszBitlist, AttestationData, SszSignature>
+    implements AttestationContainer {
 
   public static class AttestationSchema
       extends ContainerSchema3<Attestation, SszBitlist, AttestationData, SszSignature> {
@@ -91,10 +91,12 @@ public Collection<Bytes32> getDependentBlockRoots() {
     return Sets.newHashSet(getData().getTarget().getRoot(), getData().getBeaconBlockRoot());
   }
 
+  @Override
   public SszBitlist getAggregationBits() {
     return getField0();
   }
 
+  @Override
   public AttestationData getData() {
     return getField1();
   }

ethereum/spec/src/main/java/tech/pegasys/teku/spec/datastructures/operations/AttestationContainer.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright Consensys Software Inc., 2024
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+package tech.pegasys.teku.spec.datastructures.operations;
+
+import tech.pegasys.teku.infrastructure.ssz.SszContainer;
+import tech.pegasys.teku.infrastructure.ssz.SszData;
+import tech.pegasys.teku.infrastructure.ssz.collections.SszBitlist;
+
+/**
+ * Interface used to represent different types of attestations ({@link Attestation} and {@link
+ * tech.pegasys.teku.spec.datastructures.state.PendingAttestation})
+ */
+public interface AttestationContainer extends SszData, SszContainer {
+
+  AttestationData getData();
+
+  SszBitlist getAggregationBits();
+}

ethereum/spec/src/main/java/tech/pegasys/teku/spec/datastructures/state/PendingAttestation.java

@@ -22,10 +22,12 @@
 import tech.pegasys.teku.infrastructure.ssz.tree.TreeNode;
 import tech.pegasys.teku.infrastructure.unsigned.UInt64;
 import tech.pegasys.teku.spec.config.SpecConfig;
+import tech.pegasys.teku.spec.datastructures.operations.AttestationContainer;
 import tech.pegasys.teku.spec.datastructures.operations.AttestationData;
 
 public class PendingAttestation
-    extends Container4<PendingAttestation, SszBitlist, AttestationData, SszUInt64, SszUInt64> {
+    extends Container4<PendingAttestation, SszBitlist, AttestationData, SszUInt64, SszUInt64>
+    implements AttestationContainer {
 
   public static class PendingAttestationSchema
       extends ContainerSchema4<
@@ -82,10 +84,12 @@ public PendingAttestationSchema getSchema() {
     return (PendingAttestationSchema) super.getSchema();
   }
 
+  @Override
   public SszBitlist getAggregationBits() {
     return getField0();
   }
 
+  @Override
   public AttestationData getData() {
     return getField1();
   }

ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/common/util/AttestationUtil.java

@@ -38,6 +38,7 @@
 import tech.pegasys.teku.spec.datastructures.attestation.ValidatableAttestation;
 import tech.pegasys.teku.spec.datastructures.blocks.BeaconBlockSummary;
 import tech.pegasys.teku.spec.datastructures.operations.Attestation;
+import tech.pegasys.teku.spec.datastructures.operations.AttestationContainer;
 import tech.pegasys.teku.spec.datastructures.operations.AttestationData;
 import tech.pegasys.teku.spec.datastructures.operations.IndexedAttestation;
 import tech.pegasys.teku.spec.datastructures.operations.IndexedAttestation.IndexedAttestationSchema;
@@ -98,8 +99,7 @@ public boolean isSlashableAttestationData(
    */
   public IndexedAttestation getIndexedAttestation(
       final BeaconState state, final Attestation attestation) {
-    final List<Integer> attestingIndices =
-        getAttestingIndices(state, attestation.getData(), attestation.getAggregationBits());
+    final List<Integer> attestingIndices = getAttestingIndices(state, attestation);
 
     final IndexedAttestationSchema indexedAttestationSchema =
         schemaDefinitions.getIndexedAttestationSchema();
@@ -116,28 +116,31 @@ public IndexedAttestation getIndexedAttestation(
    * Return the sorted attesting indices corresponding to ``data`` and ``bits``.
    *
    * @param state
-   * @param data
-   * @param bits
+   * @param attestation
    * @return
    * @throws IllegalArgumentException
    * @see
-   *     <a>https://github.com/ethereum/consensus-specs/blob/v0.8.0/specs/core/0_beacon-chain.md#get_attesting_indices</a>
+   *     <a>https://github.com/ethereum/consensus-specs/blob/dev/specs/phase0/beacon-chain.md#get_attesting_indices</a>
    */
   public IntList getAttestingIndices(
-      final BeaconState state, final AttestationData data, final SszBitlist bits) {
-    return IntList.of(streamAttestingIndices(state, data, bits).toArray());
+      final BeaconState state, final AttestationContainer attestation) {
+    return IntList.of(streamAttestingIndices(state, attestation).toArray());
   }
 
   public IntStream streamAttestingIndices(
-      final BeaconState state, final AttestationData data, final SszBitlist bits) {
-    IntList committee =
+      final BeaconState state, final AttestationContainer attestation) {
+    final AttestationData data = attestation.getData();
+    final SszBitlist aggregationBits = attestation.getAggregationBits();
+    final IntList committee =
         beaconStateAccessors.getBeaconCommittee(state, data.getSlot(), data.getIndex());
     checkArgument(
-        bits.size() == committee.size(),
+        aggregationBits.size() == committee.size(),
         "Aggregation bitlist size (%s) does not match committee size (%s)",
-        bits.size(),
+        aggregationBits.size(),
         committee.size());
-    return IntStream.range(0, committee.size()).filter(bits::getBit).map(committee::getInt);
+    return IntStream.range(0, committee.size())
+        .filter(aggregationBits::getBit)
+        .map(committee::getInt);
   }
 
   public AttestationProcessingResult isValidIndexedAttestation(

ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/altair/forktransition/AltairStateUpgrade.java

@@ -102,7 +102,7 @@ private void translateParticipation(
       // Apply flags to all attesting validators
       final SszMutableList<SszByte> epochParticipation = state.getPreviousEpochParticipation();
       attestationUtil
-          .streamAttestingIndices(state, data, attestation.getAggregationBits())
+          .streamAttestingIndices(state, attestation)
           .forEach(
               index -> {
                 final byte previousFlags = epochParticipation.get(index).get();

ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/phase0/statetransition/epoch/ValidatorStatusFactoryPhase0.java

@@ -96,7 +96,7 @@ protected void processParticipation(
 
               // Apply flags to attestingIndices
               attestationUtil
-                  .streamAttestingIndices(state, data, attestation.getAggregationBits())
+                  .streamAttestingIndices(state, attestation)
                   .mapToObj(statuses::get)
                   .forEach(updates::apply);
             });

ethereum/statetransition/src/main/java/tech/pegasys/teku/statetransition/validation/AggregateAttestationValidator.java

@@ -142,9 +142,7 @@ private SafeFuture<InternalValidationResult> verifyAggregate(
               final BeaconState state = maybeState.get();
 
               // [REJECT] The aggregate attestation has participants
-              final IntList attestingIndices =
-                  spec.getAttestingIndices(
-                      state, aggregate.getData(), aggregate.getAggregationBits());
+              final IntList attestingIndices = spec.getAttestingIndices(state, aggregate);
               if (attestingIndices.isEmpty()) {
                 return SafeFuture.completedFuture(
                     reject(