public void validateClasses(ClassLoader classLoader, List<String> classNames,
    List<CoprocessorViolation> violations) {
    for (String className : classNames) {
      validate(classLoader, className, violations);
    }
  }
This classloader implementation calls {@link #resolveClass(Class)} method for every loaded
class. It means that some extra validation will take place
<a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-12.html#jls-12.3"> according to
JLS</a>.
hbase-server/src/main/java/org/apache/hadoop/hbase/tool/coprocessor/CoprocessorValidator.java