Remove some Java API surface no longer needed

Some cruft still remains for the tests which is hard to avoid, eg getAliceBaseKey

java/java/src/main/java/org/whispersystems/libsignal/state/SessionRecord.java

@@ -45,32 +45,10 @@ public class SessionRecord {
     }
   }
 
-  public boolean hasSessionState(int version, byte[] aliceBaseKey) {
-    if (sessionState.getSessionVersion() == version &&
-        Arrays.equals(aliceBaseKey, sessionState.getAliceBaseKey()))
-    {
-      return true;
-    }
-
-    for (SessionState state : previousStates) {
-      if (state.getSessionVersion() == version &&
-          Arrays.equals(aliceBaseKey, state.getAliceBaseKey()))
-      {
-        return true;
-      }
-    }
-
-    return false;
-  }
-
   public SessionState getSessionState() {
     return sessionState;
   }
 
-  public boolean isFresh() {
-    return fresh;
-  }
-
   /**
    * Move the current {@link SessionState} into the list of "previous" session states,
    * and replace the current {@link org.whispersystems.libsignal.state.SessionState}
@@ -80,7 +58,7 @@ public class SessionRecord {
     promoteState(new SessionState());
   }
 
-  public void promoteState(SessionState promotedState) {
+  private void promoteState(SessionState promotedState) {
     this.previousStates.addFirst(sessionState);
     this.sessionState = promotedState;
 
@@ -89,10 +67,6 @@ public class SessionRecord {
     }
   }
 
-  public void setState(SessionState sessionState) {
-    this.sessionState = sessionState;
-  }
-
   /**
    * @return a serialized version of the current SessionRecord.
    */

java/java/src/main/java/org/whispersystems/libsignal/state/SessionState.java

@@ -83,11 +83,11 @@ public class SessionState {
     this.sessionStructure = sessionStructure;
   }
 
-  public SessionState(SessionState copy) {
+  SessionState(SessionState copy) {
     this.sessionStructure = copy.sessionStructure.toBuilder().build();
   }
 
-  public SessionStructure getStructure() {
+  SessionStructure getStructure() {
     return sessionStructure;
   }
 
@@ -123,27 +123,6 @@ public class SessionState {
     }
   }
 
-  public int getPreviousCounter() {
-    return sessionStructure.getPreviousCounter();
-  }
-
-  public ECPublicKey getSenderRatchetKey() {
-    try {
-      return Curve.decodePoint(sessionStructure.getSenderChain().getSenderRatchetKey().toByteArray(), 0);
-    } catch (InvalidKeyException e) {
-      throw new AssertionError(e);
-    }
-  }
-
-  public ECKeyPair getSenderRatchetKeyPair() {
-    ECPublicKey  publicKey  = getSenderRatchetKey();
-    ECPrivateKey privateKey = Curve.decodePrivatePoint(sessionStructure.getSenderChain()
-                                                                       .getSenderRatchetKeyPrivate()
-                                                                       .toByteArray());
-
-    return new ECKeyPair(publicKey, privateKey);
-  }
-
   public boolean hasSenderChain() {
     return sessionStructure.hasSenderChain();
   }