refactored XAResourceHolder's interface + made implementation thread-safe
refactored XAResourceHolder's interface + made implementation thread-safe

pgbsl/btm,bitronix/btm,bitronix/btm,marcus-nl/btm,veresh/btm,leogong/btm,sshankar/btm,Everteam-Software/btm,brettwooldridge/btm,sshankar/btm,gavioto/btm,tomsorgie/btm,tomsorgie/btm,veresh/btm,marcus-nl/btm,pgbsl/btm,gavioto/btm,Everteam-Software/btm,leogong/btm,brettwooldridge/btm