update after review

Signed-off-by: Stefan Pingel <stefan.pingel@consensys.net>

enclave/src/main/java/org/hyperledger/besu/enclave/types/ReceiveRequest.java

@@ -28,6 +28,10 @@ public ReceiveRequest(
     this.to = to;
   }
 
+  public ReceiveRequest(final String key) {
+    this(key, null);
+  }
+
   public String getKey() {
     return key;
   }

enclave/src/main/java/org/hyperledger/besu/enclave/types/ReceiveResponse.java

@@ -21,8 +21,8 @@
 @JsonPropertyOrder({"payload", "privacyGroupId"})
 public class ReceiveResponse {
 
-  private byte[] payload;
-  private String privacyGroupId;
+  private final byte[] payload;
+  private final String privacyGroupId;
 
   @JsonCreator
   public ReceiveResponse(

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/precompiles/privacy/PrivacyPrecompiledContract.java

@@ -86,7 +86,7 @@ public Gas gasRequirement(final BytesValue input) {
   @Override
   public BytesValue compute(final BytesValue input, final MessageFrame messageFrame) {
     final String key = BytesValues.asBase64String(input);
-    final ReceiveRequest receiveRequest = new ReceiveRequest(key, null);
+    final ReceiveRequest receiveRequest = new ReceiveRequest(key);
 
     final ReceiveResponse receiveResponse;
     try {

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/privacy/PrivateTransactionHandler.java

@@ -107,7 +107,7 @@ public String getPrivacyGroup(final String key, final PrivateTransaction private
     try {
       receiveResponse = enclave.receive(receiveRequest);
       return receiveResponse.getPrivacyGroupId();
-    } catch (final Exception e) {
+    } catch (final RuntimeException e) {
       LOG.error("Failed to retrieve private transaction in enclave", e);
       throw e;
     }