corrected use of BOTH in MLKEMPrivateKeyParameters.

Removed null checks on "both" construction for ML-KEM and ML-DSA

Author: dghgit

core/src/main/java/org/bouncycastle/pqc/crypto/mlkem/MLKEMPrivateKeyParameters.java

@@ -81,7 +81,7 @@ public MLKEMPrivateKeyParameters(MLKEMParameters params, byte[] encoding, MLKEMP
             }
         }
 
-        this.prefFormat = BOTH;
+        this.prefFormat = (seed == null) ? EXPANDED_KEY : BOTH;
     }
 
     private MLKEMPrivateKeyParameters(MLKEMPrivateKeyParameters params, int preferredFormat)

core/src/main/java/org/bouncycastle/pqc/crypto/util/PrivateKeyInfoFactory.java

@@ -395,16 +395,10 @@ private static XMSSPrivateKey xmssCreateKeyStructure(XMSSPrivateKeyParameters ke
     private static ASN1Sequence getBasicPQCEncoding(byte[] seed, byte[] expanded)
     {
         ASN1EncodableVector v = new ASN1EncodableVector(2);
-        
-        if (seed != null)
-        {
-            v.add(new DEROctetString(seed));
-        }
 
-        if (expanded != null)
-        {
-            v.add(new DEROctetString(expanded));
-        }
+        v.add(new DEROctetString(seed));
+
+        v.add(new DEROctetString(expanded));
 
         return new DERSequence(v);
     }