Correct attestation aggregation while producing block (#11388)

The `aggregationBitsByAttestationData ` was not correctly utilized.
Maybe it works but a bit implicitly, so trying to fix it

cl/beacon/handler/block_production.go

@@ -1080,36 +1080,39 @@ func (a *ApiHandler) findBestAttestationsForBlockProduction(
 	sort.Slice(attestationCandidates, func(i, j int) bool {
 		return attestationCandidates[i].reward > attestationCandidates[j].reward
 	})
+
 	// Some aggregates can be supersets of existing ones so let's filter out the supersets
 	// this MAP is HashTreeRoot(AttestationData) => AggregationBits
-	aggregationBitsByAttestationData := make(map[libcommon.Hash][]byte)
+	hashToMergedAtt := make(map[libcommon.Hash]*solid.Attestation)
 	for _, candidate := range attestationCandidates {
 		// Check if it is a superset of a pre-included attestation with higher reward
 		attestationDataRoot, err := candidate.attestation.AttestantionData().HashSSZ()
 		if err != nil {
 			log.Warn("[Block Production] Cannot compute attestation data root", "err", err)
 			continue
 		}
-		currAggregationBits, exists := aggregationBitsByAttestationData[attestationDataRoot]
-		if exists {
-			if utils.IsNonStrictSupersetBitlist(
+		if curAtt, exists := hashToMergedAtt[attestationDataRoot]; exists {
+			currAggregationBits := curAtt.AggregationBits()
+			if !utils.IsNonStrictSupersetBitlist(
 				currAggregationBits,
 				candidate.attestation.AggregationBits(),
 			) {
-				continue
+				// merge if not a superset
+				utils.MergeBitlists(currAggregationBits, candidate.attestation.AggregationBits())
+				curAtt.SetAggregationBits(currAggregationBits)
 			}
-			utils.MergeBitlists(currAggregationBits, candidate.attestation.AggregationBits())
 		} else {
-			currAggregationBits = candidate.attestation.AggregationBits()
+			// Update the currently built superset
+			hashToMergedAtt[attestationDataRoot] = candidate.attestation.Copy()
 		}
-		// Update the currently built superset
-		aggregationBitsByAttestationData[attestationDataRoot] = currAggregationBits
 
-		ret.Append(candidate.attestation)
-		if ret.Len() >= int(a.beaconChainCfg.MaxAttestations) {
+		if len(hashToMergedAtt) >= int(a.beaconChainCfg.MaxAttestations) {
 			break
 		}
 	}
+	for _, att := range hashToMergedAtt {
+		ret.Append(att)
+	}
 	return ret
 }
 

cl/cltypes/solid/attestation.go

@@ -104,12 +104,16 @@ func (a *Attestation) UnmarshalJSON(buf []byte) error {
 
 // AggregationBits returns the aggregation bits buffer of the Attestation instance.
 func (a *Attestation) AggregationBits() []byte {
-	return a.aggregationBitsBuffer
+	buf := make([]byte, len(a.aggregationBitsBuffer))
+	copy(buf, a.aggregationBitsBuffer)
+	return buf
 }
 
 // SetAggregationBits sets the aggregation bits buffer of the Attestation instance.
 func (a *Attestation) SetAggregationBits(bits []byte) {
-	a.aggregationBitsBuffer = bits
+	buf := make([]byte, len(bits))
+	copy(buf, bits)
+	a.aggregationBitsBuffer = buf
 }
 
 // AttestantionData returns the attestation data of the Attestation instance.