class StringUtilTest {

    @Test
    @DisplayName("Should join single element without delimiter")
    void testJoinSingleElement() {
        String result = StringUtil.join(",", "hello");
        assertEquals("hello", result);
    }

    @Test
    @DisplayName("Should join two elements with delimiter")
    void testJoinTwoElements() {
        String result = StringUtil.join(",", "hello", "world");

                append(tempBuf, StringEscapeUtils.escapeJson(e.getKey()), () -> StringEscapeUtils.escapeJson(e.getValue().getHotThreads()));
                return tempBuf.toString();
            }).collect(Collectors.joining(","));
            buf.append(hotThreads).append(',');
        } catch (final Exception e) {
            appendException(buf, e).append(',');
        }

        appendTimestamp(buf);
        buf.append('}');

                                + "=new String[]{" + labelSet.stream().map(s -> "\"" + s + "\"").collect(Collectors.joining(",")) + "}");
                        return builder.setScript(script);
                    }
                } catch (final Exception e) {
                    logger.warn("Failed to process search hit: {}", hit, e);

        }

        @SuppressWarnings("unchecked")
        final List<String> virtualHostList = (List<String>) dataMap.get(fessConfig.getIndexFieldVirtualHost());
        if (virtualHostList != null && !virtualHostList.isEmpty()) {
            buf.append(";v=");
            buf.append(virtualHostList.stream().sorted().collect(Collectors.joining(",")));
        }

            append(b, "used", () -> p.getUsed().getBytes()).append(',');
            append(b, "capacity", () -> p.getTotalCapacity().getBytes()).append('}');
            return b.toString();
        }).collect(Collectors.joining(",")));
        buf.append("},");
        final GarbageCollectors gc = jvmStats.getGc();
        buf.append("\"gc\":{");
        buf.append(Arrays.stream(gc.getCollectors()).map(c -> {

                    .collect(Collectors.joining(","));
            buf.append('[').append(json).append(']');
        } else if (value instanceof List) {
            final String json = ((List<?>) value).stream()
                    .map(s -> "\"" + StringEscapeUtils.escapeJson(s.toString()) + "\"")
                    .collect(Collectors.joining(","));
            buf.append('[').append(json).append(']');

                .filter(StringUtil::isNotBlank)
                .distinct()
                .collect(Collectors.joining("\n")));
        body.virtualHosts = stream(entity.getVirtualHosts())
                .get(stream -> stream.filter(StringUtil::isNotBlank).distinct().map(String::trim).collect(Collectors.joining("\n")));
        return body;
    }

                return StringUtils.join(newInputs, ",");
            }
            return StringUtils.join(newInputs, ",") + "=>" + StringUtils.join(newOutputs, ",");
        }
        if (Arrays.equals(inputs, outputs)) {
            return StringUtils.join(inputs, ",");
        }
        return StringUtils.join(inputs, ",") + "=>" + StringUtils.join(outputs, ",");
    }

                            logger.warn("{}", errors.stream().collect(Collectors.joining(", ")));
                            if (auth.isDebugActive() && StringUtil.isNotBlank(auth.getLastErrorReason())) {
                                logger.warn("Authentication Failure: {} - Reason: {}", errors.stream().collect(Collectors.joining(", ")),
                                        auth.getLastErrorReason());

        return messageManager.toMessageList(request.getLocale() == null ? Locale.ENGLISH : request.getLocale(), messages)
                .stream()
                .collect(Collectors.joining(" "));
    }

    /**
     * Determines whether the current request is authorized to access the API endpoint.
     * This default implementation returns false, requiring subclasses to override