Method dropNullPlaceholders

external/jsoncpp/jsoncpp.cpp:4486–4486

void FastWriter::enableYAMLCompatibility() { yamlCompatibilityEnabled_ = true; }

void FastWriter::dropNullPlaceholders() { dropNullPlaceholders_ = true; }

void FastWriter::omitEndingLineFeed() { omitEndingLineFeed_ = true; }