"MBeanInfo contents for an MXBean" section in MXBean specification has the following sentence:
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The Descriptor for each of these objects will also have a field originalType that is a
string representing the Java type that appeared in the MXBean interface. *For a generic
Java type, this is the string returned by toString()*. For a class or primitive type, this
is the string returned by Class.getName().
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  About "For a generic Java type, this is the string returned by toString()"...
  The javadoc for javax.management.Descriptor says:

--
originalType:
For a non-generic type, the string value is the value returned by Class.getName(). For a
parameterized type such as Map<String,Integer> it is *a string representation of the type,
with the raw type followed by the actual type arguments in angle brackets separated by
commas without spaces*, for example "java.util.Map<java.lang.String,java.lang.Integer>".
--

  Consider the type: List<String>
  The originalType: "java.util.List<java.lang.String>"
  - and this won't be returned by var.getClass().toString()