public String getUtf8StringWithoutLineEnding() {
        if (bytes == null) {
            return "";
        }
        return new String(bytes, 0, bytes.length - determineLineEndingLength(bytes), StandardCharsets.UTF_8);
    }
Holds exactly one complete line of container output. Lines are split on newline characters (LF, CR LF).
core/src/main/java/org/testcontainers/containers/output/OutputFrame.java