Include exception cause in applicable ReadWriteSplittingSQLExceptions (#415)

### By submitting this pull request, I confirm that my contribution is
made under the terms of the Apache 2.0 license.

Author: aaron-congo

wrapper/src/main/java/software/amazon/jdbc/plugin/readwritesplitting/ReadWriteSplittingPlugin.java

@@ -295,7 +295,7 @@ void switchConnectionIfRequired(final boolean readOnly) throws SQLException {
         } catch (final SQLException e) {
           if (!isConnectionUsable(currentConnection)) {
             logAndThrowException(Messages.get("ReadWriteSplittingPlugin.errorSwitchingToReader"),
-                SqlState.CONNECTION_UNABLE_TO_CONNECT);
+                SqlState.CONNECTION_UNABLE_TO_CONNECT, e);
             return;
           }
 
@@ -318,7 +318,7 @@ void switchConnectionIfRequired(final boolean readOnly) throws SQLException {
           switchToWriterConnection(hosts);
         } catch (final SQLException e) {
           logAndThrowException(Messages.get("ReadWriteSplittingPlugin.errorSwitchingToWriter"),
-              SqlState.CONNECTION_UNABLE_TO_CONNECT);
+              SqlState.CONNECTION_UNABLE_TO_CONNECT, e);
         }
       }
     }
@@ -335,6 +335,13 @@ private void logAndThrowException(final String logMessage, final SqlState sqlSta
     throw new ReadWriteSplittingSQLException(logMessage, sqlState.getState());
   }
 
+  private void logAndThrowException(
+      final String logMessage, final SqlState sqlState, final Throwable cause)
+      throws SQLException {
+    LOGGER.severe(logMessage);
+    throw new ReadWriteSplittingSQLException(logMessage, sqlState.getState(), cause);
+  }
+
   private synchronized void switchToWriterConnection(
       final List<HostSpec> hosts)
       throws SQLException {

wrapper/src/test/java/integration/refactored/container/tests/ReadWriteSplittingTests.java

@@ -53,7 +53,6 @@
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
 import java.util.stream.Collectors;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.MethodOrderer;
 import org.junit.jupiter.api.TestMethodOrder;
 import org.junit.jupiter.api.TestTemplate;