Break out EppResourceInput subclasses

This frankenclass was starting to get a little cluttered, especially once I add the ChildEntityInput/Reader.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117266882

java/com/google/domain/registry/mapreduce/inputs/EppResourceInputs.java

@@ -0,0 +1,81 @@
+// Copyright 2016 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.domain.registry.mapreduce.inputs;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Predicates.not;
+import static com.google.common.collect.Iterables.all;
+import static com.google.common.collect.Lists.asList;
+import static com.google.domain.registry.util.TypeUtils.hasAnnotation;
+
+import com.google.appengine.tools.mapreduce.Input;
+import com.google.common.collect.ImmutableSet;
+import com.google.domain.registry.model.EppResource;
+import com.google.domain.registry.model.index.EppResourceIndex;
+
+import com.googlecode.objectify.Key;
+import com.googlecode.objectify.annotation.EntitySubclass;
+
+/**
+ * Mapreduce helpers for {@link EppResource} keys and objects.
+ *
+ * <p>The inputs provided by this class are not deletion-aware and do not project the resources
+ * forward in time. That is the responsibility of mappers that use these inputs.
+ */
+public final class EppResourceInputs {
+
+  private EppResourceInputs() {}
+
+  /** Returns a MapReduce {@link Input} that loads all {@link EppResourceIndex} objects. */
+  public static <R extends EppResource> Input<EppResourceIndex> createIndexInput() {
+    return new EppResourceIndexInput();
+  }
+
+  /**
+   * Returns a MapReduce {@link Input} that loads all {@link EppResource} objects of a given type,
+   * including deleted resources.
+   *
+   * <p>Note: Do not concatenate multiple EntityInputs together (this is inefficient as it iterates
+   * through all buckets multiple times). Specify the types in a single input, or load all types by
+   * specifying {@link EppResource} as the class.
+   */
+  @SafeVarargs
+  public static <R extends EppResource> Input<R> createEntityInput(
+      Class<? extends R> resourceClass,
+      Class<? extends R>... moreResourceClasses) {
+    return new EppResourceEntityInput<R>(
+        ImmutableSet.copyOf(asList(resourceClass, moreResourceClasses)));
+  }
+
+  /**
+   * Returns a MapReduce {@link Input} that loads keys to all {@link EppResource} objects of a given
+   * type, including deleted resources.
+   *
+   * <p>Note: Do not concatenate multiple KeyInputs together (this is inefficient as it iterates
+   * through all buckets multiple times). Specify the types in a single input, or load all types by
+   * specifying {@link EppResource} as the class.
+   */
+  @SafeVarargs
+  public static <R extends EppResource> Input<Key<R>> createKeyInput(
+      Class<? extends R> resourceClass,
+      Class<? extends R>... moreResourceClasses) {
+    ImmutableSet<Class<? extends R>> resourceClasses =
+        ImmutableSet.copyOf(asList(resourceClass, moreResourceClasses));
+    checkArgument(
+        all(resourceClasses, not(hasAnnotation(EntitySubclass.class))),
+        "Mapping over keys requires a non-polymorphic Entity");
+    return new EppResourceKeyInput<>(resourceClasses);
+  }
+}