in ecs-logging-core/src/main/java/co/elastic/logging/EcsJsonSerializer.java [130:141]
public static void serializeLogLevel(StringBuilder builder, String level) {
builder.append("\"log.level\":");
// add padding so that all levels line up
// WARN
// ERROR
for (int i = 5 - level.length(); i > 0; i--) {
builder.append(' ');
}
builder.append('\"');
JsonUtils.quoteAsString(level, builder);
builder.append("\",");
}