chore!: remove deprecated getCollections() methods (#307)

* Remove deprecated Firestore#getCollections() method. Use Firestore#listCollections() instead * Remove deprecated DocumentReference#getCollections() method. Use DocumentReference#listCollections() instead

Author: BenWhitehead

google-cloud-firestore/clirr-ignored-differences.xml

@@ -17,23 +17,17 @@
 
 <!-- see http://www.mojohaus.org/clirr-maven-plugin/examples/ignored-differences.html -->
 <differences>
- <!-- TODO: Remove after release of 1.33.0 -->
- <difference>
- <differenceType>7012</differenceType>
- <className>com/google/cloud/firestore/Firestore</className>
- <method>com.google.api.core.ApiFuture runAsyncTransaction(*)</method>
- </difference>
 
+ <!-- v2.0.0 -->
  <difference>
- <differenceType>7005</differenceType>
- <className>com/google/cloud/firestore/*</className>
- <method>*(com.google.cloud.firestore.FirestoreImpl, *)</method>
- <to>*(com.google.cloud.firestore.FirestoreRpcContext, *)</to>
+ <differenceType>7002</differenceType>
+ <className>com/google/cloud/firestore/DocumentReference</className>
+ <method>java.lang.Iterable getCollections()</method>
  </difference>
  <difference>
- <differenceType>7009</differenceType>
- <className>com/google/cloud/firestore/*</className>
- <method>*(com.google.cloud.firestore.FirestoreImpl, *)</method>
+ <differenceType>7002</differenceType>
+ <className>com/google/cloud/firestore/Firestore</className>
+ <method>java.lang.Iterable getCollections()</method>
  </difference>
 
  <!--

google-cloud-firestore/src/main/java/com/google/cloud/firestore/DocumentReference.java

@@ -416,19 +416,6 @@ public void remove() {
  };
  }
 
- /**
- * Fetches the subcollections that are direct children of this document.
- *
- * @deprecated Use {@link #listCollections()}.
- * @throws FirestoreException if the Iterable could not be initialized.
- * @return An Iterable that can be used to fetch all subcollections.
- */
- @Deprecated
- @Nonnull
- public Iterable<CollectionReference> getCollections() {
- return listCollections();
- }
-
  /**
  * Starts listening to the document referenced by this DocumentReference.
  *

google-cloud-firestore/src/main/java/com/google/cloud/firestore/Firestore.java

@@ -55,17 +55,6 @@ public interface Firestore extends Service<FirestoreOptions>, AutoCloseable {
  @Nonnull
  Iterable<CollectionReference> listCollections();
 
- /**
- * Fetches the root collections that are associated with this Firestore database.
- *
- * @deprecated Use {@link #listCollections()}.
- * @throws FirestoreException if the Iterable could not be initialized.
- * @return An Iterable that can be used to fetch all collections.
- */
- @Deprecated
- @Nonnull
- Iterable<CollectionReference> getCollections();
-
  /**
  * Creates and returns a new @link{Query} that includes all documents in the database that are
  * contained in a collection or subcollection with the given @code{collectionId}.

google-cloud-firestore/src/main/java/com/google/cloud/firestore/FirestoreImpl.java

@@ -120,12 +120,6 @@ public Iterable<CollectionReference> listCollections() {
  return rootDocument.listCollections();
  }
 
- @Nonnull
- @Override
- public Iterable<CollectionReference> getCollections() {
- return listCollections();
- }
-
  @Nonnull
  @Override
  public ApiFuture<List<DocumentSnapshot>> getAll(