Fix stripe-java on JDK 1.5 by dropping String.isEmpty call
Fix stripe-java on JDK 1.5 by dropping String.isEmpty call

stripe/stripe-java,AdamStelmaszczyk/stripe-java,shalecraig/stripe-java,kbouzidi/stripe-java,ebroder/stripe-java,rgarbi/stripe-java,zs-engg/stripe-sdk,hardtoe/stripe-java