Wrote a paser for MXBean attribute name ( form of <[SystemProperties."java.class.version"]>) and edit test unit to indicate behaviors at corner cases.
Modify Extractor's timer to use timer.cancel() instead of an extra flag.
Added getSupportedType() to get the DataType supported
Revert "Added getSupportedType() to get the DataType supported"

This reverts commit 614634735996ca21a4a7f2060446a3ba5056c2e6.
Rename checkTypeOf() to supportTypeOf()
implemented multi layered attribute