question: public void clearTransactions ( int fromHeight ) { lock . lock ( ) ; try { if ( fromHeight == 0 ) { unspent . clear ( ) ; spent . clear ( ) ; pending . clear ( ) ; dead . clear ( ) ; transactions . clear ( ) ; } else { throw new UnsupportedOperationException ( ) ; } } finally { lock . unlock ( ) ; } }
target:  Deletes transactions which appeared above the given block height from the wallet, but does not touch the keys. This is useful if you have some keys and wish to replay the block chain into the wallet in order to pick them up.