Clarify behavior of the protocol level responseTimeout and the connection management level socketTimeout and their interrelation

Author: LichKing-lee

httpclient5/src/main/java/org/apache/hc/client5/http/config/ConnectionConfig.java

@@ -149,7 +149,15 @@ public Builder setSocketTimeout(final int soTimeout, final TimeUnit timeUnit) {
         }
 
         /**
-         * Determines the default socket timeout value for I/O operations.
+         * Determines the default socket timeout value for I/O operations on
+         * connections created by this configuration.
+         * A timeout value of zero is interpreted as an infinite timeout.
+         * <p>
+         * This value acts as a baseline at the connection management layer.
+         * This parameter overrides the socket timeout setting applied at the I/O layer
+         * and in its tuen can overridden by settings applied at the protocol layer
+         * for the duration of a message exchange.
+         * </p>
          * <p>
          * Default: {@code null} (undefined)
          * </p>

httpclient5/src/main/java/org/apache/hc/client5/http/config/RequestConfig.java

@@ -517,6 +517,10 @@ public Builder setConnectTimeout(final long connectTimeout, final TimeUnit timeU
          * HTTP transports with message multiplexing.
          * </p>
          * <p>
+         * This parameter overrides the socket timeout setting applied at the connection
+         * management or I/O layers for the duration of a message exchange.
+         * </p>
+         * <p>
          * Please note that response timeout is not a deadline. Its absolute value
          * can be exceeded, for example, in case of automatic request re-execution.
          * Please make sure the automatic request re-execution policy has been