demo-protobuf/src/main/java/com/github/shoothzj/demo/protobuf/module/AddressBookProtos.java
public Builder clearEmail() {
        bitField0_ = (bitField0_ & ~0x00000004);
        email_ = getDefaultInstance().getEmail();
        onChanged();
        return this;
      }
/**
       * <code>optional string email = 3;</code>
       * @return This builder for chaining.
       */
optional string email = 3;
@return This builder for chaining.
optional string email = 3 ; @return This builder for chaining .
public Builder clearEmail() {
        bitField0_ = (bitField0_ & ~0x00000004);
        email_ = getDefaultInstance().getEmail();
        onChanged();
        return this;
      }
public Builder clearEmail ( ) { bitField0_ = ( bitField0_ & ~ 0x00000004 ) ; email_ = getDefaultInstance ( ) . getEmail ( ) ; onChanged ( ) ; return this ; }
<code>optional string email = 3;</code>
 @return This builder for chaining.
<code > optional string email = 3 ; < / code > @return This builder for chaining .