public Builder clearSource() {
                bitField0_ = (bitField0_ & ~0x00000002);
                source_ = 0;
                onChanged();
                return this;
            }
<code>optional .jraft.FileSource source = 2;</code>
jraft-core/src/main/java/com/alipay/sofa/jraft/entity/LocalFileMetaOutter.java