RawSecretKeyFactoryTest uses deprecated Assert.assertThat method

RawSecretKeyFactoryTest checks if, given either the key or the key specification, the server can generate the missing one, and it will match the original. It does this with two methods:

• shouldGenerateSecretKeyFromSecretKeySpec()
• shouldGenerateSecretKeySpecFromSecretKey()

This check is performed using using the method assertThat(), from the package org.junit.Assert. It has been deprecated in favour of another method called assertThat, from the package org.hamcrest.MatcherAssert. The class should be updated to use the new assertThat method.