Major Description
The javadoc for org.apache.logging.log4j.core.util.Charsets gives the impression that the class was somehow copied from code in the JDK. In reviewing the code it is clear that the purpose of the class was to make a version of the charset constants defined in Java 7 and beyond available in Java 6. As such, the names of the constants will necessarily be similar and there is only one reasonable way to initialize them.
The javadoc should be changed to make it clear what the purpose of the class is and identify the constants as a reference to the StandardCharsets class.