code: func (f *FormatEncoder) EncodeEntry(entry zapcore.Entry, fields []zapcore.Field) (*buffer.Buffer, error) {
  	line := f.pool.Get()
  	for _, f := range f.formatters {
  		f.Format(line, entry, fields)
  	}
  
  	encodedFields, err := f.Encoder.EncodeEntry(entry, fields)
  	if err != nil {
  		return nil, err
  	}
  	if line.Len() > 0 && encodedFields.Len() != 1 {
  		line.AppendString(" ")
  	}
  	line.AppendString(encodedFields.String())
  	encodedFields.Free()
  
  	return line, nil
  }
docs: // EncodeEntry formats a zap log record. The structured fields are formatted by a
  // zapcore.ConsoleEncoder and are appended as JSON to the end of the formatted entry.
  // All entries are terminated by a newline.