Fixed spelling of default batch execution handler

Author: oliemansm

src/main/java/graphql/servlet/DeafultBatchExecutionHandler.java renamed to src/main/java/graphql/servlet/DefaultBatchExecutionHandler.java

@@ -8,7 +8,7 @@
 import java.util.Iterator;
 import java.util.function.BiFunction;
 
-public class DeafultBatchExecutionHandler implements BatchExecutionHandler {
+public class DefaultBatchExecutionHandler implements BatchExecutionHandler {
 
     @Override
     public void handleBatch(GraphQLBatchedInvocationInput batchedInvocationInput, Writer writer, GraphQLObjectMapper graphQLObjectMapper,

src/main/java/graphql/servlet/GraphQLQueryInvoker.java

@@ -100,7 +100,7 @@ public static class Builder {
         private Supplier<Instrumentation> getInstrumentation = () -> SimpleInstrumentation.INSTANCE;
         private Supplier<PreparsedDocumentProvider> getPreparsedDocumentProvider = () -> NoOpPreparsedDocumentProvider.INSTANCE;
         private Supplier<DataLoaderDispatcherInstrumentationOptions> dataLoaderDispatcherInstrumentationOptionsSupplier = DataLoaderDispatcherInstrumentationOptions::newOptions;
-        private BatchExecutionHandler batchExecutionHandler = new DeafultBatchExecutionHandler();
+        private BatchExecutionHandler batchExecutionHandler = new DefaultBatchExecutionHandler();
 
         public Builder withExecutionStrategyProvider(ExecutionStrategyProvider provider) {
             return withExecutionStrategyProvider(() -> provider);