Remove RepositoryMethodReference from RepositoryItemReaderBuilder

This class and its usage have been reported to be confusing and
causing context startup failures without real added value.

This commit removes that class to simplify the creation
of a RepositoryItemReader through its builder.

Resolves #793

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/builder/RepositoryItemReaderBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 the original author or authors.
+ * Copyright 2017-2022 the original author or authors.
  *
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -53,8 +53,6 @@ public class RepositoryItemReaderBuilder<T> {
 
 	private String methodName;
 
-	private RepositoryMethodReference<?> repositoryMethodReference;
-
 	private boolean saveState = true;
 
 	private String name;
@@ -186,43 +184,11 @@ public class RepositoryItemReaderBuilder<T> {
 		return this;
 	}
 
-	/**
-	 * Specifies a repository and the type-safe method to call for the reader. The method
-	 * configured via this mechanism must take
-	 * {@link org.springframework.data.domain.Pageable} as the <em>last</em> argument.
-	 * This method can be used in place of
-	 * {@link #repository(PagingAndSortingRepository)}, {@link #methodName(String)}, and
-	 * {@link #arguments(List)}.
-	 *
-	 * Note: The repository that is used by the repositoryMethodReference must be
-	 * non-final.
-	 * @param repositoryMethodReference of the used to get a repository and type-safe
-	 * method for use by the reader.
-	 * @return The current instance of the builder.
-	 * @see RepositoryItemReader#setMethodName(String)
-	 * @see RepositoryItemReader#setRepository(PagingAndSortingRepository)
-	 *
-	 */
-	public RepositoryItemReaderBuilder<T> repository(RepositoryMethodReference<?> repositoryMethodReference) {
-		this.repositoryMethodReference = repositoryMethodReference;
-
-		return this;
-	}
-
 	/**
 	 * Builds the {@link RepositoryItemReader}.
 	 * @return a {@link RepositoryItemReader}
 	 */
 	public RepositoryItemReader<T> build() {
-		if (this.repositoryMethodReference != null) {
-			this.methodName = this.repositoryMethodReference.getMethodName();
-			this.repository = this.repositoryMethodReference.getRepository();
-
-			if (CollectionUtils.isEmpty(this.arguments)) {
-				this.arguments = this.repositoryMethodReference.getArguments();
-			}
-		}
-
 		Assert.notNull(this.sorts, "sorts map is required.");
 		Assert.notNull(this.repository, "repository is required.");
 		Assert.hasText(this.methodName, "methodName is required.");
@@ -243,77 +209,4 @@ public class RepositoryItemReaderBuilder<T> {
 		return reader;
 	}
 
-	/**
-	 * Establishes a proxy that will capture a the Repository and the associated
-	 * methodName that will be used by the reader.
-	 *
-	 * @param <T> The type of repository that will be used by the reader. The class must
-	 * not be final.
-	 */
-	public static class RepositoryMethodReference<T> {
-
-		private RepositoryMethodInterceptor repositoryInvocationHandler;
-
-		private PagingAndSortingRepository<?, ?> repository;
-
-		public RepositoryMethodReference(PagingAndSortingRepository<?, ?> repository) {
-			this.repository = repository;
-			this.repositoryInvocationHandler = new RepositoryMethodInterceptor();
-		}
-
-		/**
-		 * The proxy returned prevents actual method execution and is only used to gather,
-		 * information about the method.
-		 * @return T is a proxy of the object passed in in the constructor
-		 */
-		@SuppressWarnings("unchecked")
-		public T methodIs() {
-			Enhancer enhancer = new Enhancer();
-			enhancer.setSuperclass(this.repository.getClass());
-			enhancer.setCallback(this.repositoryInvocationHandler);
-			return (T) enhancer.create();
-		}
-
-		PagingAndSortingRepository<?, ?> getRepository() {
-			return this.repository;
-		}
-
-		String getMethodName() {
-			return this.repositoryInvocationHandler.getMethodName();
-		}
-
-		List<Object> getArguments() {
-			return this.repositoryInvocationHandler.getArguments();
-		}
-
-	}
-
-	private static class RepositoryMethodInterceptor implements MethodInterceptor {
-
-		private String methodName;
-
-		private List<Object> arguments;
-
-		@Override
-		public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
-			this.methodName = method.getName();
-			if (objects != null && objects.length > 1) {
-				arguments = new ArrayList<>(Arrays.asList(objects));
-				// remove last entry because that will be provided by the
-				// RepositoryItemReader
-				arguments.remove(objects.length - 1);
-			}
-			return null;
-		}
-
-		String getMethodName() {
-			return this.methodName;
-		}
-
-		List<Object> getArguments() {
-			return arguments;
-		}
-
-	}
-
 }