various improvements

hibernate-core/src/main/java/org/hibernate/StatelessSession.java

@@ -54,8 +54,8 @@
  * Certain rules applying to stateful sessions are relaxed in a stateless
  * session:
  * <ul>
- * <li>it is not necessary to discard a session and its entities after an
- *     exception is thrown by a stateless sessions, and
+ * <li>it's not necessary to discard a stateless session and its entities
+ *     after an exception is thrown by the stateless session, and
  * <li>when an exception is thrown by a stateless session, the current
  *     transaction is not automatically marked for rollback.
  * </ul>

hibernate-core/src/main/java/org/hibernate/boot/registry/classloading/internal/AggregatedClassLoader.java

@@ -10,7 +10,6 @@
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 
-import org.hibernate.internal.util.ExceptionHelper;
 
 public class AggregatedClassLoader extends ClassLoader {
 	private final ClassLoader[] individualClassLoaders;
@@ -122,7 +121,7 @@ else if ( !sysCLReturned && systemClassLoader != null ) {
 
 	private Iterator<ClassLoader> newTcclNeverIterator() {
 		final ClassLoader systemClassLoader = locateSystemClassLoader();
-		return new Iterator<ClassLoader>() {
+		return new Iterator<>() {
 			private int currentIndex = 0;
 			private boolean sysCLReturned = false;
 
@@ -182,7 +181,7 @@ public URL nextElement() {
 
 	@Override
 	protected URL findResource(String name) {
-		final Iterator<ClassLoader> clIterator = newClassLoaderIterator();
+		final var clIterator = newClassLoaderIterator();
 		while ( clIterator.hasNext() ) {
 			final ClassLoader classLoader = clIterator.next();
 			final URL resource = classLoader.getResource( name );
@@ -195,22 +194,18 @@ protected URL findResource(String name) {
 
 	@Override
 	protected Class<?> findClass(String name) throws ClassNotFoundException {
-		final Iterator<ClassLoader> clIterator = newClassLoaderIterator();
-		Throwable t = null;
+		final var clIterator = newClassLoaderIterator();
+		final var exception = new ClassNotFoundException( "Could not load requested class: " + name );
 		while ( clIterator.hasNext() ) {
 			final ClassLoader classLoader = clIterator.next();
 			try {
 				return classLoader.loadClass( name );
 			}
-			catch (Exception ex) {
-				ExceptionHelper.combine( ( t == null ? t = new Throwable() : t ), ex );
-			}
-			catch (LinkageError le) {
-				ExceptionHelper.combine( ( t == null ? t = new Throwable() : t ), le );
+			catch (Exception|LinkageError ex) {
+				exception.addSuppressed( ex );
 			}
 		}
-
-		throw new ClassNotFoundException( "Could not load requested class : " + name, ( t != null && t.getSuppressed().length > 0 ? t : null ) );
+		throw exception;
 	}
 
 	private static ClassLoader locateSystemClassLoader() {

hibernate-core/src/main/java/org/hibernate/collection/spi/AbstractPersistentCollection.java

@@ -195,8 +195,8 @@ public int getSize() {
 			final CollectionEntry entry = session.getPersistenceContextInternal().getCollectionEntry( this );
 			if ( entry == null ) {
 				throwLazyInitializationExceptionIfNotConnected();
-				throwLazyInitializationException("collection not associated with session");
-				throw new AssertionFailure("impossible");
+				throwLazyInitializationException( "collection not associated with session" );
+				throw new AssertionFailure( "impossible" );
 			}
 			else {
 				if ( hasQueuedOperations() ) {
@@ -233,23 +233,23 @@ private <T> T withTemporarySessionIfNeeded(LazyInitializationWork<T> lazyInitial
 				tempSession = openTemporarySessionForLoading();
 			}
 			else {
-				throwLazyInitializationException( "could not initialize proxy - no Session" );
+				throwLazyInitializationException( "no session" );
 			}
 		}
 		else if ( !session.isOpenOrWaitingForAutoClose() ) {
 			if ( allowLoadOutsideTransaction ) {
 				tempSession = openTemporarySessionForLoading();
 			}
 			else {
-				throwLazyInitializationException( "could not initialize proxy - the owning Session was closed" );
+				throwLazyInitializationException( "the owning session was closed" );
 			}
 		}
 		else if ( !session.isConnected() ) {
 			if ( allowLoadOutsideTransaction ) {
 				tempSession = openTemporarySessionForLoading();
 			}
 			else {
-				throwLazyInitializationException( "could not initialize proxy - the owning Session is disconnected" );
+				throwLazyInitializationException( "the owning session is disconnected" );
 			}
 		}
 
@@ -273,8 +273,7 @@ else if ( !session.isConnected() ) {
 				}
 
 				final CollectionPersister collectionDescriptor =
-						session.getSessionFactory()
-								.getMappingMetamodel()
+						session.getSessionFactory().getMappingMetamodel()
 								.getCollectionDescriptor( getRole() );
 				session.getPersistenceContextInternal()
 						.addUninitializedDetachedCollection( collectionDescriptor, this );
@@ -301,20 +300,22 @@ else if ( !session.isConnected() ) {
 			else {
 				// Whenever the collection lazy loading is triggered during the loading process,
 				// closing the connection will cause an error when RowProcessingStateStandardImpl#next() will be called.
-				final PersistenceContext persistenceContext = session.getPersistenceContext();
-				if ( !session.isTransactionInProgress()
-						&& ( !persistenceContext.hasLoadContext()
-							|| persistenceContext.hasLoadContext()
-								&& persistenceContext.getLoadContexts().isLoadingFinished() ) ) {
+				if ( !session.isTransactionInProgress() && !unfinishedLoading() ) {
 					session.getJdbcCoordinator().afterTransaction();
 				}
 			}
 		}
 	}
 
+	private boolean unfinishedLoading() {
+		final PersistenceContext persistenceContext = session.getPersistenceContext();
+		return persistenceContext.hasLoadContext()
+			&& !persistenceContext.getLoadContexts().isLoadingFinished();
+	}
+
 	private SharedSessionContractImplementor openTemporarySessionForLoading() {
 		if ( sessionFactoryUuid == null ) {
-			throwLazyInitializationException( "SessionFactory UUID not known to create temporary Session for loading" );
+			throwLazyInitializationException( "SessionFactory UUID not known; cannot create temporary session for loading" );
 		}
 
 		final SessionImplementor session =
@@ -373,8 +374,8 @@ public boolean elementExists(Object element) {
 		final CollectionEntry entry = session.getPersistenceContextInternal().getCollectionEntry( this );
 		if ( entry == null ) {
 			throwLazyInitializationExceptionIfNotConnected();
-			throwLazyInitializationException("collection not associated with session");
-			throw new AssertionFailure("impossible");
+			throwLazyInitializationException( "collection not associated with session" );
+			throw new AssertionFailure( "impossible" );
 		}
 		else {
 			if ( hasQueuedOperations() ) {
@@ -427,8 +428,8 @@ public Object elementByIndex(Object index) {
 		final CollectionEntry entry = session.getPersistenceContextInternal().getCollectionEntry( this );
 		if ( entry == null ) {
 			throwLazyInitializationExceptionIfNotConnected();
-			throwLazyInitializationException("collection not associated with session");
-			throw new AssertionFailure("impossible");
+			throwLazyInitializationException( "collection not associated with session" );
+			throw new AssertionFailure( "impossible" );
 		}
 		else {
 			if ( hasQueuedOperations() ) {
@@ -646,9 +647,8 @@ private void throwLazyInitializationExceptionIfNotConnected() {
 
 	private void throwLazyInitializationException(String message) {
 		throw new LazyInitializationException(
-				"failed to lazily initialize a collection" +
-						(role == null ? "" : " of role: " + role) +
-						": " + message
+				String.format( "Cannot lazily initialize collection%s (%s)",
+						role == null ? "" : " of role '" + role + "'", message )
 		);
 	}
 
@@ -1305,11 +1305,7 @@ protected static <E> Collection<E> getOrphans(
 					currentSaving.add( current );
 				}
 				else {
-					final Object currentId = getEntityIdentifierIfNotUnsaved(
-							entityName,
-							current,
-							session
-					);
+					final Object currentId = getEntityIdentifierIfNotUnsaved( entityName, current, session );
 					currentIds.add( useIdDirect ? currentId : new TypedValue( idType, currentId ) );
 				}
 			}

hibernate-core/src/main/java/org/hibernate/internal/SessionImpl.java

@@ -721,7 +721,7 @@ private void firePersist(final PersistEvent event) {
 			}
 		}
 		if ( originalException != null ) {
-			ExceptionHelper.doThrow( originalException );
+			ExceptionHelper.rethrow( originalException );
 		}
 	}
 

hibernate-core/src/main/java/org/hibernate/internal/util/ExceptionHelper.java

@@ -11,37 +11,28 @@ private ExceptionHelper() {
 	}
 
 	/**
-	 * Throws the given throwable even if it is a checked exception.
+	 * Throws the given {@link Throwable}, even if it's a checked exception.
 	 *
-	 * @param e The throwable to throw.
+	 * @param throwable The {@code Throwable} to throw.
 	 */
-	public static void doThrow(Throwable e) {
-		ExceptionHelper.doThrow0(e);
+	public static void rethrow(Throwable throwable) {
+		sneakyThrow( throwable );
 	}
 
-	public static Throwable getRootCause(Throwable error) {
-		Throwable toProcess = error;
-		while ( toProcess.getCause() != null ) {
-			toProcess = toProcess.getCause();
-		}
-		return toProcess;
+	@SuppressWarnings("unchecked")
+	private static <T extends Throwable> void sneakyThrow(Throwable e)
+			throws T {
+		throw (T) e;
 	}
 
-	public static <T extends Throwable> T combine(T throwable, T otherThrowable) {
-		T toThrow = throwable;
-		if ( otherThrowable != null ) {
-			if ( toThrow != null ) {
-				toThrow.addSuppressed( otherThrowable );
-			}
-			else {
-				toThrow = otherThrowable;
+	public static Throwable getRootCause(Throwable error) {
+		var next = error;
+		while ( true ) {
+			final var current = next;
+			next = current.getCause();
+			if ( next == null ) {
+				return current;
 			}
 		}
-		return toThrow;
-	}
-
-	@SuppressWarnings("unchecked")
-	private static <T extends Throwable> void doThrow0(Throwable e) throws T {
-		throw (T) e;
 	}
 }

hibernate-core/src/main/java/org/hibernate/resource/transaction/backend/jdbc/internal/DdlTransactionIsolatorNonJtaImpl.java

@@ -122,7 +122,7 @@ public void release() {
 				}
 			}
 			if ( originalException != null ) {
-				ExceptionHelper.doThrow( originalException );
+				ExceptionHelper.rethrow( originalException );
 			}
 		}
 	}

hibernate-core/src/test/java/org/hibernate/orm/test/actionqueue/CustomBeforeCompletionTest.java

@@ -30,12 +30,7 @@ public class CustomBeforeCompletionTest extends BaseCoreFunctionalTestCase {
 	public void success() {
 		inSession( session -> {
 			AtomicBoolean called = new AtomicBoolean( false );
-			session.getActionQueue().registerProcess( new BeforeTransactionCompletionProcess() {
-				@Override
-				public void doBeforeTransactionCompletion(SessionImplementor session) {
-					called.set( true );
-				}
-			} );
+			session.getActionQueue().registerProcess( s -> called.set( true ) );
 			Assert.assertFalse( called.get() );
 			inTransaction( session, theSession -> {
 				theSession.persist( new SimpleEntity( "jack" ) );