GH-5723: cleanup and polishing

Apache HttpClient Factory

  - Removed the unconditional evictIdleConnections(...) call
  - Added a guard so idle eviction is only configured when
idleConnectionTimeoutMs > 0
  - Also removed the duplicate evictExpiredConnections() that was
present in the original

SparqlProtocolSession

Case-insensitive match: replaced startsWith("charset=") with
regionMatches(true, 0, "charset=", 0, 8) — the true flag makes it
case-insensitive, so CHARSET=, Charset=, etc. all match.
  2. Quote stripping: after extracting the value, checks for surrounding
double-quotes and strips them, handling charset="UTF-8".

HttpUtils

UnsupportedCharsetException is a subclass of IllegalArgumentException,
so catching IllegalArgumentException covers both it and
IllegalCharsetNameException in one clause — no need for multiple catches

Author: aschwarte10

core/http/client-apache5/src/main/java/org/eclipse/rdf4j/http/client/apache5/ApacheHC5RDF4JHttpClientFactory.java

@@ -104,11 +104,14 @@ public RDF4JHttpClient create(RDF4JHttpClientConfig config) {
 				.evictExpiredConnections()
 				.setConnectionManager(connectionManager)
 				.setDefaultRequestConfig(requestConfig)
-				.evictExpiredConnections()
-				.evictIdleConnections(TimeValue.ofMilliseconds(config.getIdleConnectionTimeoutMs()))
 				.useSystemProperties()
-				.setRetryStrategy(new RDF4JRetryStrategy(config.getMaxConnectionsPerRoute()))
-				.setRedirectStrategy(DefaultRedirectStrategy.INSTANCE);
+				.setRetryStrategy(new RDF4JRetryStrategy(config.getMaxConnectionsPerRoute()));
+
+		if (config.getIdleConnectionTimeoutMs() > 0) {
+			builder.evictIdleConnections(TimeValue.ofMilliseconds(config.getIdleConnectionTimeoutMs()));
+		}
+
+		builder.setRedirectStrategy(DefaultRedirectStrategy.INSTANCE);
 
 		if (!config.getDefaultHeaders().isEmpty()) {
 			List<BasicHeader> defaultHeaders = config.getDefaultHeaders()

core/http/client-api/src/main/java/org/eclipse/rdf4j/http/client/spi/HttpUtils.java

@@ -90,7 +90,7 @@ private static Charset parseCharset(String contentType, Charset defaultCharset)
 				}
 				try {
 					return Charset.forName(name);
-				} catch (UnsupportedCharsetException e) {
+				} catch (IllegalArgumentException e) {
 					return defaultCharset;
 				}
 			}

core/http/client/src/main/java/org/eclipse/rdf4j/http/client/SPARQLProtocolSession.java

@@ -1173,8 +1173,14 @@ Optional<Charset> getResponseCharset(HttpResponse response) {
 		for (HttpHeader header : headers) {
 			for (String part : header.getValue().split(";")) {
 				String trimmed = part.trim();
-				if (trimmed.startsWith("charset=")) {
+				if (trimmed.regionMatches(true, 0, "charset=", 0, "charset=".length())) {
 					String charsetName = trimmed.substring("charset=".length()).trim();
+					// Strip optional surrounding quotes (e.g. charset="UTF-8")
+					if (charsetName.length() >= 2
+							&& charsetName.charAt(0) == '"'
+							&& charsetName.charAt(charsetName.length() - 1) == '"') {
+						charsetName = charsetName.substring(1, charsetName.length() - 1);
+					}
 					try {
 						Charset charset = Charset.forName(charsetName);
 						logger.debug("response charset is {}", charset);