Transaction object: {
"hash", "from":"0x...", "to":"0x...", "value":..., "gasPrice":..., "gasLimit":..., "nonce":..., "input":"BA5E64",
(followings are unused now:)
"r":"...", "s":"...", "v":"...",
(followings are optional, only available when mined in a block:)
"blockHash":"0x...", "blockNumber":..., "indexInBlock":...,
(followings are optional, belongs to receipt:)
"contractAddress":"0x....", "gasUsed":..., "cumulativeGasUsed":..., "root":"..."
(timestamps:)
"timeCreated":..., (when created here)
"timePending":..., (when seen as pending transaction)
"timeMined":..., (when included in a block)
"timeExist":... (==timeCreated when created here, or ==timePending when seen in pending transactions, or ==timeMined when mined in a block),
"timeNoticed":... (when queried and saved)
}

Transaction info object: {
"hash", "from":"0x...", "to":"0x...", "value":...,
(followings are optional, only available when mined in a block:)
"blockHash":"0x...", "blockNumber":..., "indexInBlock":...,
(followings are optional, belongs to receipt:)
"contractAddress":"0x....",
(timestamps:)
"timeExist":... (==timeCreated when created here, or ==timePending when seen in pending transactions, or ==timeMined when mined in a block)
}

GET /api/tx/{hash}: returns 404, or 200 with tx object
GET /api/account/{address}/txinfos: returns 404, or 200 with array of tx info objects

ISSUE: web3j could not parse pending transactions returned by ethGetTransaction correctly (missed block number)

Change:
GET /api/account/{address}/txinfos
to:
GET /api/tx/info: returns 404, or 200 with array of tx info objects of all addresses belong to the user

Transaction synchronization is needed, in another task T54.