clazz has been used in Java in place of the reserved word "class" since JDK 1.0. "class" is what you want, but abbreviating or inserting junk ("a", "the", "_", etc) reduces clarity. clazz just says class. "International" English speakers (those reading both British and American English) are used to transposing 's' and 'z'.
Since Java has had disclosed source and a suitable culture right from the start, worthwhile Java code and tutorials pick up the same conventions. That's one of the great things about the Java ecosystem, which I think has been an important part of its success.
