ObjectsNonNull.java

import static java.util.Objects.requireNonNull;
...

// throws a NullPointerException when null
requireNonNull(employee);

// throws a NullPointerException with a message
requireNonNull(employee, "employee reference is null");

// throws a NullPointerException with a message from a supplier function
requireNonNull(employee, () -> errorMsgProducer.getNullMessage("employee"));

// do paycheck stuff ...