Android referr string only returns first parameter

When I set up a BroadcastReceiver for a referrer string, for example, and test the receiver as this , log for String referrerString = extras.getString("referrer");

only returns the first parameter utm_source=test_source

and nothing after the "&" concatenation.

Why when I use a string with parameter "&" (for example referrer=utm_source=test_source&utm_medium=test_medium...

) is it only the first parameter returned, but when I create the parameters with google style (for example referrer=utm_source%3Dtest_source%26utm_medium%3Dtest_medium...

) the whole string is returned?