Core JUnit tests: type arguments, unused imports

core/java/test/junit/net/i2p/client/I2PSessionTest.java

...nit/net/i2p/client/naming/BlockfileNamingServiceTest.java

core/java/test/junit/net/i2p/crypto/ElGamalTest.java

core/java/test/junit/net/i2p/crypto/SHA256Test.java

...java/test/junit/net/i2p/crypto/SessionEncryptionTest.java

core/java/test/junit/net/i2p/data/PayloadTest.java

core/java/test/junit/net/i2p/data/RouterAddressTest.java

core/java/test/junit/net/i2p/data/RouterInfoTest.java

...java/test/junit/net/i2p/data/SimpleDataStructureTest.java

...st/junit/net/i2p/data/i2cp/MessagePayloadMessageTest.java

...unit/net/i2p/data/i2cp/SendMessageExpiresMessageTest.java

.../test/junit/net/i2p/data/i2cp/SendMessageMessageTest.java

core/java/test/junit/net/i2p/stat/SimpleStatDumper.java

core/java/test/junit/net/i2p/stat/StatLogSplitter.java