Why is this an issue?
Most of the time a block of code is empty when a piece of code is really missing. So such empty block must be either filled or removed.
Noncompliant code example
for (int i = 0; i < 42; i++){} // Empty on purpose or missing piece of code ?
Exceptions
When a block contains a comment, this block is not considered to be empty.
while and unless loops are also exception to the rule.
while (order.processNext()); // Compliant
