public Set<String> getSearchPackages() {
        return searchPackages;
    }
Returns a set of package names that can be searched for {@link HashFormat} implementations according to
heuristics defined in the {@link #getHashFormatClass(String, String) getHashFormat(packageName, token)} JavaDoc.
<h3>Efficiency</h3>
Configuring this property is not as efficient as configuring a {@link #getFormatClassNames() formatClassNames}
map, but it may be more convenient depending on the number of {@code HashFormat} implementations that
need to be supported by this factory.

@return a set of package names that can be searched for {@link HashFormat} implementations
@see #getHashFormatClass(String, String)
crypto/hash/src/main/java/org/apache/shiro/crypto/hash/format/DefaultHashFormatFactory.java