The extension number type doesn't match specification

[MatkovIvan]

By specification, the extension number must be 32 bit unsigned integer.
But the current implementation is

CorrelationVector-Java/src/main/java/com/microsoft/correlationvector/CorrelationVector.java

Line 47 in 1012460

private final AtomicInteger extension;

So, the max value is 2147483647 instead of 4294967295.
Also, there are no tests for that.

Related issue: microsoft/CorrelationVector-CSharp#15