down integrate to svn

1 files changed, 17 insertions, 0 deletions

diff --git a/java/src/main/java/com/google/protobuf/UnknownFieldSet.java b/java/src/main/java/com/google/protobuf/UnknownFieldSet.java
index 45e2e6e4..81432b40 100644
--- a/java/src/main/java/com/google/protobuf/UnknownFieldSet.java
+++ b/java/src/main/java/com/google/protobuf/UnknownFieldSet.java
@@ -91,6 +91,7 @@ public final class UnknownFieldSet implements MessageLite {
   }
   private Map<Integer, Field> fields;
 
+
   @Override
   public boolean equals(final Object other) {
     if (this == other) {
@@ -367,6 +368,22 @@ public final class UnknownFieldSet implements MessageLite {
       reinitialize();
       return this;
     }
+    
+    /** Clear fields from the set with a given field number. */
+    public Builder clearField(final int number) {
+      if (number == 0) {
+        throw new IllegalArgumentException("Zero is not a valid field number.");
+      }
+      if (lastField != null && lastFieldNumber == number) {
+        // Discard this.
+        lastField = null;
+        lastFieldNumber = 0;
+      }
+      if (fields.containsKey(number)) {
+        fields.remove(number);
+      }
+      return this;
+    }
 
     /**
      * Merge the fields from {@code other} into this set.  If a field number