Updated scanCallback comment.
Updated scanCallback comment.

Stratio/aerospike-client-java,pradeepsrinivasan/aerospike-client-java,wgpshashank/aerospike-client-java,alexandrnikitin/aerospike-client-java,wgpshashank/aerospike-client-java,pradeepsrinivasan/aerospike-client-java,Stratio/aerospike-client-java,alexandrnikitin/aerospike-client-java