Document TransactionsLayer.getAllBySender() nonce ordering invariant

Signed-off-by: Fabio Di Fabio <fabio.difabio@consensys.net>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: fab-10

CHANGELOG.md

@@ -13,6 +13,7 @@
 - Dispatch snap server request processing (GET_ACCOUNT_RANGE, GET_STORAGE_RANGE, GET_BYTECODES, GET_TRIE_NODES, GET_BLOCK_ACCESS_LISTS) off the Netty event loop to prevent heavy trie/DB work from blocking ETH protocol message handling [#10083](https://github.com/besu-eth/besu/pull/10083)
 - Add DiscV5 discovery metrics (`discv5_live_nodes_current`, `discv5_total_nodes_current`) to track node counts in the routing table [#9692](https://github.com/besu-eth/besu/issues/9692)
 - Add `txpool_contentFrom` JSON-RPC method [#10111](https://github.com/besu-eth/besu/pull/10111)
+- Add `txpool_content` JSON-RPC method [#10120](https://github.com/besu-eth/besu/pull/10120)
 
 ## 26.3.0
 

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/transactions/layered/TransactionsLayer.java

@@ -87,6 +87,17 @@ void blockAdded(
 
   List<PendingTransaction> getAll();
 
+  /**
+   * Returns all pending transactions across all layers, grouped by sender and sorted by nonce in
+   * ascending order per sender.
+   *
+   * <p>The nonce ordering relies on each layer's internal {@code NavigableMap<Long,
+   * PendingTransaction>} being nonce-sorted, and on the invariant that a layer always holds
+   * lower-nonce transactions than its next layer (e.g. ready transactions before sparse ones).
+   *
+   * @return a map from sender address to the list of that sender's pending transactions, sorted by
+   *     nonce ascending
+   */
   Map<Address, List<PendingTransaction>> getAllBySender();
 
   /**