Block builder used to iterate mempool chunks in mining order while assembling a block.
Declared in <txmempool.h>
[[guarded_by(0x7fbc8f682fa8), guarded_by(0x7fbc95d44d08), guarded_by(0x7fbca708a9c8), guarded_by(0x7fbc86273268), guarded_by(0x7fbca7897948), guarded_by(0x7fbc84ab8f98), guarded_by(0x7fbc870f8498), guarded_by(0x7fbc921dfd58)]]
mutable
std::unique_ptr<TxGraph::BlockBuilder> m_builder;