rpc: fix Bloom filter response (#321)

* fix bloomfilter in rpc response

* add comments

ethereum/rpc/backend/backend.go

@@ -204,7 +204,7 @@ func (e *EVMBackend) EthBlockFromTendermint(
 		}
 	}
 
-	blockBloomResp, err := e.queryClient.BlockBloom(types.ContextWithHeight(block.Height), &evmtypes.QueryBlockBloomRequest{})
+	blockBloomResp, err := e.queryClient.BlockBloom(types.ContextWithHeight(block.Height), &evmtypes.QueryBlockBloomRequest{Height: block.Height})
 	if err != nil {
 		e.logger.Debug("failed to query BlockBloom", "height", block.Height, "error", err.Error())
 
@@ -266,7 +266,7 @@ func (e *EVMBackend) HeaderByNumber(blockNum types.BlockNumber) (*ethtypes.Heade
 		return nil, err
 	}
 
-	req := &evmtypes.QueryBlockBloomRequest{}
+	req := &evmtypes.QueryBlockBloomRequest{Height: resBlock.Block.Height}
 
 	blockBloomResp, err := e.queryClient.BlockBloom(types.ContextWithHeight(resBlock.Block.Height), req)
 	if err != nil {
@@ -287,7 +287,7 @@ func (e *EVMBackend) HeaderByHash(blockHash common.Hash) (*ethtypes.Header, erro
 		return nil, err
 	}
 
-	req := &evmtypes.QueryBlockBloomRequest{}
+	req := &evmtypes.QueryBlockBloomRequest{Height: resBlock.Block.Height}
 
 	blockBloomResp, err := e.queryClient.BlockBloom(types.ContextWithHeight(resBlock.Block.Height), req)
 	if err != nil {

ethereum/rpc/types/block.go

@@ -30,6 +30,7 @@ func NewBlockNumber(n *big.Int) BlockNumber {
 
 // ContextWithHeight wraps a context with the a gRPC block height header. If the provided height is
 // 0, it will return an empty context and the gRPC query will use the latest block height for querying.
+// Note that all metadata are processed and removed by tendermint layer, so it wont be accessible at gRPC server level.
 func ContextWithHeight(height int64) context.Context {
 	if height == 0 {
 		return context.Background()