Allow unused return on various Protobuf methods.

java/core/src/main/java/com/google/protobuf/AbstractProtobufList.java

@@ -77,6 +77,7 @@ public int hashCode() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean add(E e) {
     ensureIsMutable();
     return super.add(e);
@@ -89,12 +90,14 @@ public void add(int index, E element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends E> c) {
     ensureIsMutable();
     return super.addAll(c);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(int index, Collection<? extends E> c) {
     ensureIsMutable();
     return super.addAll(index, c);
@@ -119,12 +122,14 @@ public final void makeImmutable() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public E remove(int index) {
     ensureIsMutable();
     return super.remove(index);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean remove(Object o) {
     ensureIsMutable();
     int index = indexOf(o);
@@ -136,18 +141,21 @@ public boolean remove(Object o) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean removeAll(Collection<?> c) {
     ensureIsMutable();
     return super.removeAll(c);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean retainAll(Collection<?> c) {
     ensureIsMutable();
     return super.retainAll(c);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public E set(int index, E element) {
     ensureIsMutable();
     return super.set(index, element);

java/core/src/main/java/com/google/protobuf/BooleanArrayList.java

@@ -157,11 +157,13 @@ public int size() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Boolean set(int index, Boolean element) {
     return setBoolean(index, element);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean setBoolean(int index, boolean element) {
     ensureIsMutable();
     ensureIndexInRange(index);
@@ -171,6 +173,7 @@ public boolean setBoolean(int index, boolean element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean add(Boolean element) {
     addBoolean(element);
     return true;
@@ -224,6 +227,7 @@ private void addBoolean(int index, boolean element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends Boolean> collection) {
     ensureIsMutable();
 
@@ -257,6 +261,7 @@ public boolean addAll(Collection<? extends Boolean> collection) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Boolean remove(int index) {
     ensureIsMutable();
     ensureIndexInRange(index);

java/core/src/main/java/com/google/protobuf/CodedInputStream.java

@@ -441,6 +441,7 @@ public abstract <T extends MessageLite> T readMessage(
    *
    * @return the old limit.
    */
+  @CanIgnoreReturnValue
   public final int setRecursionLimit(final int limit) {
     if (limit < 0) {
       throw new IllegalArgumentException("Recursion limit cannot be negative: " + limit);
@@ -464,6 +465,7 @@ public final int setRecursionLimit(final int limit) {
    *
    * @return the old limit.
    */
+  @CanIgnoreReturnValue
   public final int setSizeLimit(final int limit) {
     if (limit < 0) {
       throw new IllegalArgumentException("Size limit cannot be negative: " + limit);
@@ -522,6 +524,7 @@ final boolean shouldDiscardUnknownFields() {
    *
    * @return the old limit.
    */
+  @CanIgnoreReturnValue
   public abstract int pushLimit(int byteLimit) throws InvalidProtocolBufferException;
 
   /**
@@ -1224,6 +1227,7 @@ public void resetSizeCounter() {
     }
 
     @Override
+    @CanIgnoreReturnValue
     public int pushLimit(int byteLimit) throws InvalidProtocolBufferException {
       if (byteLimit < 0) {
         throw InvalidProtocolBufferException.negativeSize();
@@ -2000,6 +2004,7 @@ public void resetSizeCounter() {
     }
 
     @Override
+    @CanIgnoreReturnValue
     public int pushLimit(int byteLimit) throws InvalidProtocolBufferException {
       if (byteLimit < 0) {
         throw InvalidProtocolBufferException.negativeSize();

java/core/src/main/java/com/google/protobuf/DoubleArrayList.java

@@ -156,11 +156,13 @@ public int size() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Double set(int index, Double element) {
     return setDouble(index, element);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public double setDouble(int index, double element) {
     ensureIsMutable();
     ensureIndexInRange(index);
@@ -170,6 +172,7 @@ public double setDouble(int index, double element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean add(Double element) {
     addDouble(element);
     return true;
@@ -223,6 +226,7 @@ private void addDouble(int index, double element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends Double> collection) {
     ensureIsMutable();
 
@@ -256,6 +260,7 @@ public boolean addAll(Collection<? extends Double> collection) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Double remove(int index) {
     ensureIsMutable();
     ensureIndexInRange(index);

java/core/src/main/java/com/google/protobuf/FloatArrayList.java

@@ -155,11 +155,13 @@ public int size() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Float set(int index, Float element) {
     return setFloat(index, element);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public float setFloat(int index, float element) {
     ensureIsMutable();
     ensureIndexInRange(index);
@@ -169,6 +171,7 @@ public float setFloat(int index, float element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean add(Float element) {
     addFloat(element);
     return true;
@@ -222,6 +225,7 @@ private void addFloat(int index, float element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends Float> collection) {
     ensureIsMutable();
 
@@ -255,6 +259,7 @@ public boolean addAll(Collection<? extends Float> collection) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Float remove(int index) {
     ensureIsMutable();
     ensureIndexInRange(index);

java/core/src/main/java/com/google/protobuf/IntArrayList.java

@@ -155,11 +155,13 @@ public int size() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Integer set(int index, Integer element) {
     return setInt(index, element);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public int setInt(int index, int element) {
     ensureIsMutable();
     ensureIndexInRange(index);
@@ -169,6 +171,7 @@ public int setInt(int index, int element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean add(Integer element) {
     addInt(element);
     return true;
@@ -222,6 +225,7 @@ private void addInt(int index, int element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends Integer> collection) {
     ensureIsMutable();
 
@@ -255,6 +259,7 @@ public boolean addAll(Collection<? extends Integer> collection) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Integer remove(int index) {
     ensureIsMutable();
     ensureIndexInRange(index);

java/core/src/main/java/com/google/protobuf/Internal.java

@@ -36,6 +36,7 @@ private Internal() {}
   static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
 
   /** Throws an appropriate {@link NullPointerException} if the given objects is {@code null}. */
+  @CanIgnoreReturnValue
   static <T> T checkNotNull(T obj) {
     if (obj == null) {
       throw new NullPointerException();
@@ -44,6 +45,7 @@ static <T> T checkNotNull(T obj) {
   }
 
   /** Throws an appropriate {@link NullPointerException} if the given objects is {@code null}. */
+  @CanIgnoreReturnValue
   static <T> T checkNotNull(T obj, String message) {
     if (obj == null) {
       throw new NullPointerException(message);

java/core/src/main/java/com/google/protobuf/InvalidProtocolBufferException.java

@@ -46,6 +46,7 @@ public InvalidProtocolBufferException(String description, IOException e) {
    *
    * @return this
    */
+  @CanIgnoreReturnValue
   public InvalidProtocolBufferException setUnfinishedMessage(MessageLite unfinishedMessage) {
     this.unfinishedMessage = unfinishedMessage;
     return this;

java/core/src/main/java/com/google/protobuf/LazyFieldLite.java

@@ -242,6 +242,7 @@ public MessageLite getValue() {
    * <p>LazyField is not thread-safe for write access. Synchronizations are needed under read/write
    * situations.
    */
+  @CanIgnoreReturnValue
   public MessageLite setValue(MessageLite value) {
     MessageLite originalValue = this.value;
     this.delayedBytes = null;

java/core/src/main/java/com/google/protobuf/LazyStringArrayList.java

@@ -161,6 +161,7 @@ public void add(byte[] element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends String> c) {
     // The default implementation of AbstractCollection.addAll(Collection)
     // delegates to add(Object). This implementation instead delegates to
@@ -170,6 +171,7 @@ public boolean addAll(Collection<? extends String> c) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(int index, Collection<? extends String> c) {
     ensureIsMutable();
     // When copying from another LazyStringList, directly copy the underlying
@@ -182,6 +184,7 @@ public boolean addAll(int index, Collection<? extends String> c) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAllByteString(Collection<? extends ByteString> values) {
     ensureIsMutable();
     boolean ret = list.addAll(values);
@@ -190,6 +193,7 @@ public boolean addAllByteString(Collection<? extends ByteString> values) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAllByteArray(Collection<byte[]> c) {
     ensureIsMutable();
     boolean ret = list.addAll(c);
@@ -198,6 +202,7 @@ public boolean addAllByteArray(Collection<byte[]> c) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public String remove(int index) {
     ensureIsMutable();
     Object o = list.remove(index);
@@ -238,6 +243,7 @@ public byte[] getByteArray(int index) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public String set(int index, String s) {
     ensureIsMutable();
     Object o = list.set(index, s);
@@ -254,11 +260,13 @@ public void set(int index, byte[] s) {
     setAndReturn(index, s);
   }
 
+  @CanIgnoreReturnValue
   private Object setAndReturn(int index, ByteString s) {
     ensureIsMutable();
     return list.set(index, s);
   }
 
+  @CanIgnoreReturnValue
   private Object setAndReturn(int index, byte[] s) {
     ensureIsMutable();
     return list.set(index, s);

java/core/src/main/java/com/google/protobuf/LongArrayList.java

@@ -155,11 +155,13 @@ public int size() {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Long set(int index, Long element) {
     return setLong(index, element);
   }
 
   @Override
+  @CanIgnoreReturnValue
   public long setLong(int index, long element) {
     ensureIsMutable();
     ensureIndexInRange(index);
@@ -169,6 +171,7 @@ public long setLong(int index, long element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean add(Long element) {
     addLong(element);
     return true;
@@ -222,6 +225,7 @@ private void addLong(int index, long element) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public boolean addAll(Collection<? extends Long> collection) {
     ensureIsMutable();
 
@@ -255,6 +259,7 @@ public boolean addAll(Collection<? extends Long> collection) {
   }
 
   @Override
+  @CanIgnoreReturnValue
   public Long remove(int index) {
     ensureIsMutable();
     ensureIndexInRange(index);