Add proper nullability annotations to Firestore.

Additionally remove uses of the redundant @publicapi annotation.

Author: vkryachko

firebase-firestore/firebase-firestore.gradle

@@ -20,7 +20,6 @@ plugins {
 firebaseLibrary {
     testLab.enabled = true
     publishSources = true
-    staticAnalysis.disableKotlinInteropLint()
 }
 
 protobuf {

firebase-firestore/src/main/java/com/google/firebase/Timestamp.java

@@ -19,7 +19,6 @@
 import android.os.Parcel;
 import android.os.Parcelable;
 import androidx.annotation.NonNull;
-import com.google.firebase.annotations.PublicApi;
 import java.util.Date;
 
 /**
@@ -35,10 +34,9 @@
  *     https://github.com/google/protobuf/blob/master/src/google/protobuf/timestamp.proto">The
  *     reference timestamp definition</a>
  */
-@PublicApi
 public final class Timestamp implements Comparable<Timestamp>, Parcelable {
 
-  @PublicApi @NonNull
+  @NonNull
   public static final Parcelable.Creator<Timestamp> CREATOR =
       new Parcelable.Creator<Timestamp>() {
         @Override
@@ -61,21 +59,19 @@ public Timestamp[] newArray(int size) {
    *     Negative second values with fractions must still have non-negative nanoseconds values that
    *     count forward in time. Must be from 0 to 999,999,999 inclusive.
    */
-  @PublicApi
   public Timestamp(long seconds, int nanoseconds) {
     validateRange(seconds, nanoseconds);
     this.seconds = seconds;
     this.nanoseconds = nanoseconds;
   }
 
-  protected Timestamp(Parcel in) {
+  protected Timestamp(@NonNull Parcel in) {
     this.seconds = in.readLong();
     this.nanoseconds = in.readInt();
   }
 
   /** Creates a new timestamp from the given date. */
-  @PublicApi
-  public Timestamp(Date date) {
+  public Timestamp(@NonNull Date date) {
     long millis = date.getTime();
     long seconds = millis / 1000;
     int nanoseconds = (int) (millis % 1000) * 1000000;
@@ -89,26 +85,22 @@ public Timestamp(Date date) {
   }
 
   /** Creates a new timestamp with the current date, with millisecond precision. */
-  @PublicApi
   @NonNull
   public static Timestamp now() {
     return new Timestamp(new Date());
   }
 
   /** Returns the seconds part of the timestamp. */
-  @PublicApi
   public long getSeconds() {
     return seconds;
   }
 
   /** Returns the sub-second part of the timestamp, in nanoseconds. */
-  @PublicApi
   public int getNanoseconds() {
     return nanoseconds;
   }
 
   /** Returns a new Date corresponding to this timestamp. This may lose precision. */
-  @PublicApi
   @NonNull
   public Date toDate() {
     return new Date(seconds * 1000 + (nanoseconds / 1000000));
@@ -120,14 +112,13 @@ public int describeContents() {
   }
 
   @Override
-  public void writeToParcel(Parcel dest, int flags) {
+  public void writeToParcel(@NonNull Parcel dest, int flags) {
     dest.writeLong(this.seconds);
     dest.writeInt(this.nanoseconds);
   }
 
   @Override
-  @PublicApi
-  public int compareTo(Timestamp other) {
+  public int compareTo(@NonNull Timestamp other) {
     if (seconds == other.seconds) {
       return Integer.signum(nanoseconds - other.nanoseconds);
     }

firebase-firestore/src/main/java/com/google/firebase/firestore/Blob.java

@@ -19,12 +19,10 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.RestrictTo;
-import com.google.firebase.annotations.PublicApi;
 import com.google.firebase.firestore.util.Util;
 import com.google.protobuf.ByteString;
 
 /** Immutable class representing an array of bytes in Firestore. */
-@PublicApi
 public class Blob implements Comparable<Blob> {
   private final ByteString bytes;
 
@@ -39,7 +37,6 @@ private Blob(ByteString bytes) {
    * @return The new Blob instance
    */
   @NonNull
-  @PublicApi
   public static Blob fromBytes(@NonNull byte[] bytes) {
     checkNotNull(bytes, "Provided bytes array must not be null.");
     return new Blob(ByteString.copyFrom(bytes));
@@ -55,7 +52,6 @@ public static Blob fromByteString(@NonNull ByteString bytes) {
 
   /** @return The bytes of this blob as a new byte[] array. */
   @NonNull
-  @PublicApi
   public byte[] toBytes() {
     return bytes.toByteArray();
   }
@@ -84,7 +80,6 @@ public int hashCode() {
   }
 
   @Override
-  @PublicApi
   public int compareTo(@NonNull Blob other) {
     int size = Math.min(bytes.size(), other.bytes.size());
     for (int i = 0; i < size; i++) {

firebase-firestore/src/main/java/com/google/firebase/firestore/CollectionReference.java

@@ -17,13 +17,12 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import com.google.android.gms.tasks.Task;
-import com.google.firebase.annotations.PublicApi;
 import com.google.firebase.firestore.model.DocumentKey;
 import com.google.firebase.firestore.model.ResourcePath;
 import com.google.firebase.firestore.util.Executors;
 import com.google.firebase.firestore.util.Util;
-import javax.annotation.Nullable;
 
 /**
  * A CollectionReference can be used for adding documents, getting document references, and querying
@@ -33,7 +32,6 @@
  * test mocks. Subclassing is not supported in production code and new SDK releases may break code
  * that does so.
  */
-@PublicApi
 public class CollectionReference extends Query {
 
   CollectionReference(ResourcePath path, FirebaseFirestore firestore) {
@@ -50,7 +48,6 @@ public class CollectionReference extends Query {
 
   /** @return The ID of the collection. */
   @NonNull
-  @PublicApi
   public String getId() {
     return query.getPath().getLastSegment();
   }
@@ -63,7 +60,6 @@ public String getId() {
    *     collection.
    */
   @Nullable
-  @PublicApi
   public DocumentReference getParent() {
     ResourcePath parentPath = query.getPath().popLast();
     if (parentPath.isEmpty()) {
@@ -80,7 +76,6 @@ public DocumentReference getParent() {
    * @return The path of this collection.
    */
   @NonNull
-  @PublicApi
   public String getPath() {
     return query.getPath().canonicalString();
   }
@@ -92,7 +87,6 @@ public String getPath() {
    * @return A DocumentReference pointing to a new document with an auto-generated ID.
    */
   @NonNull
-  @PublicApi
   public DocumentReference document() {
     return document(Util.autoId());
   }
@@ -105,7 +99,6 @@ public DocumentReference document() {
    * @return The DocumentReference instance.
    */
   @NonNull
-  @PublicApi
   public DocumentReference document(@NonNull String documentPath) {
     checkNotNull(documentPath, "Provided document path must not be null.");
     return DocumentReference.forPath(
@@ -121,7 +114,6 @@ public DocumentReference document(@NonNull String documentPath) {
    * @return A Task that will be resolved with the DocumentReference of the newly created document.
    */
   @NonNull
-  @PublicApi
   public Task<DocumentReference> add(@NonNull Object data) {
     checkNotNull(data, "Provided data must not be null.");
     final DocumentReference ref = document();

firebase-firestore/src/main/java/com/google/firebase/firestore/DocumentChange.java

@@ -17,15 +17,14 @@
 import static com.google.firebase.firestore.util.Assert.hardAssert;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
-import com.google.firebase.annotations.PublicApi;
 import com.google.firebase.firestore.core.DocumentViewChange;
 import com.google.firebase.firestore.core.ViewSnapshot;
 import com.google.firebase.firestore.model.Document;
 import com.google.firebase.firestore.model.DocumentSet;
 import java.util.ArrayList;
 import java.util.List;
-import javax.annotation.Nullable;
 
 /**
  * A DocumentChange represents a change to the documents matching a query. It contains the document
@@ -35,10 +34,8 @@
  * test mocks. Subclassing is not supported in production code and new SDK releases may break code
  * that does so.
  */
-@PublicApi
 public class DocumentChange {
   /** An enumeration of snapshot diff types. */
-  @PublicApi
   public enum Type {
     /** Indicates a new document was added to the set of documents matching the query. */
     ADDED,
@@ -91,7 +88,6 @@ public int hashCode() {
   }
 
   @NonNull
-  @PublicApi
   public Type getType() {
     return type;
   }
@@ -104,7 +100,6 @@ public Type getType() {
    *     Type.REMOVED).
    */
   @NonNull
-  @PublicApi
   public QueryDocumentSnapshot getDocument() {
     return document;
   }
@@ -114,7 +109,6 @@ public QueryDocumentSnapshot getDocument() {
    * (i.e. supposing that all prior DocumentChange objects have been applied). Returns -1 for
    * 'added' events.
    */
-  @PublicApi
   public int getOldIndex() {
     return oldIndex;
   }
@@ -124,7 +118,6 @@ public int getOldIndex() {
    * supposing that all prior DocumentChange objects and the current DocumentChange object have been
    * applied). Returns -1 for 'removed' events.
    */
-  @PublicApi
   public int getNewIndex() {
     return newIndex;
   }

firebase-firestore/src/main/java/com/google/firebase/firestore/DocumentId.java

@@ -14,7 +14,6 @@
 
 package com.google.firebase.firestore;
 
-import com.google.firebase.annotations.PublicApi;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -43,7 +42,6 @@
  * WriteBatch#set}), the property annotated by @DocumentId is ignored, which allows writing the POJO
  * back to any document, even if it's not the origin of the POJO.
  */
-@PublicApi
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ElementType.FIELD, ElementType.METHOD})
 public @interface DocumentId {}