prevent startup with privacy and goquorum modes enabled together (#1879)

Signed-off-by: Sally MacFarlane <sally.macfarlane@consensys.net>

besu/src/main/java/org/hyperledger/besu/cli/BesuCommand.java

@@ -2041,6 +2041,10 @@ public class BesuCommand implements DefaultCommandValues, Runnable {
       if (isPruningEnabled()) {
         throw new ParameterException(commandLine, String.format("%s %s", "Pruning", errorSuffix));
       }
+      if (isGoQuorumCompatibilityMode) {
+        throw new ParameterException(
+            commandLine, String.format("%s %s", "GoQuorum mode", errorSuffix));
+      }
 
       if (isPrivacyMultiTenancyEnabled
           && !jsonRpcConfiguration.isAuthenticationEnabled()

besu/src/test/java/org/hyperledger/besu/cli/BesuCommandTest.java

@@ -3413,6 +3413,23 @@ public class BesuCommandTest extends CommandTestAbstract {
     assertThat(commandOutput.toString()).isEmpty();
   }
 
+  @Test
+  public void privacyWithGoQuorumModeMustError() throws IOException {
+    final Path genesisFile =
+        createFakeGenesisFile(VALID_GENESIS_QUORUM_INTEROP_ENABLED_WITH_CHAINID);
+    parseCommand(
+        "--goquorum-compatibility-enabled",
+        "--privacy-enabled",
+        "--genesis-file",
+        genesisFile.toString(),
+        "--min-gas-price",
+        "0");
+
+    assertThat(commandErrorOutput.toString())
+        .contains("GoQuorum mode cannot be enabled with privacy.");
+    assertThat(commandOutput.toString()).isEmpty();
+  }
+
   @Rule public TemporaryFolder testFolder = new TemporaryFolder();
 
   @Test