diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptionFutureCallback.java b/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptionFutureCallback.java
index 0191294f8..1c55d047b 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptionFutureCallback.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptionFutureCallback.java
@@ -31,6 +31,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /**
+ * @param <T> the future result type returned by this callback.
  * @since 5.2
  */
 public class IgnoreCompleteExceptionFutureCallback<T> implements FutureCallback<T> {
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptonFutureCallback.java b/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptonFutureCallback.java
index b6950fd53..41c5531a4 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptonFutureCallback.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/async/methods/IgnoreCompleteExceptonFutureCallback.java
@@ -29,6 +29,7 @@ package org.apache.hc.client5.http.async.methods;
 import org.apache.hc.core5.concurrent.FutureCallback;
 
 /**
+ * @param <T> the future result type returned by this callback.
  * @deprecated Use {@link IgnoreCompleteExceptionFutureCallback}
  * @since 5.2
  */
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/classic/HttpClient.java b/httpclient5/src/main/java/org/apache/hc/client5/http/classic/HttpClient.java
index 9ddf4a1a6..026457e84 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/classic/HttpClient.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/classic/HttpClient.java
@@ -194,6 +194,7 @@ public interface HttpClient {
      * having to manage resource deallocation internally.
      * </p>
      *
+     * @param <T> the type of the value determined by the response.
      * @param request   the request to execute
      * @param responseHandler the response handler
      *
@@ -213,6 +214,7 @@ public interface HttpClient {
      * having to manage resource deallocation internally.
      * </p>
      *
+     * @param <T> the type of the value determined by the response.
      * @param request   the request to execute
      * @param context   the context to use for the execution, or
      *                  {@code null} to use the default context
@@ -237,6 +239,7 @@ public interface HttpClient {
      * having to manage resource deallocation internally.
      * </p>
      *
+     * @param <T> the type of the value determined by the response.
      * @param target    the target host for the request.
      *                  Implementations may accept {@code null}
      *                  if they can still determine a route, for example
@@ -263,6 +266,7 @@ public interface HttpClient {
      * having to manage resource deallocation internally.
      * </p>
      *
+     * @param <T> the type of the value determined by the response.
      * @param target    the target host for the request.
      *                  Implementations may accept {@code null}
      *                  if they can still determine a route, for example
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/MessageCopier.java b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/MessageCopier.java
index d562e1a7c..f0e5b7885 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/MessageCopier.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/MessageCopier.java
@@ -32,6 +32,7 @@ import org.apache.hc.core5.http.HttpMessage;
 /**
  * Abstract HTTP message copier.
  *
+ * @param <T> The type of {@link HttpMessage}.
  * @since 5.0
  *
  * @deprecated Use message builders.
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/StateHolder.java b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/StateHolder.java
index 308160dc4..7678c2602 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/StateHolder.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/StateHolder.java
@@ -29,6 +29,7 @@ package org.apache.hc.client5.http.impl;
 import org.apache.hc.core5.annotation.Internal;
 
 /**
+ * @param <T> The type of object to store and restore.
  * @since 5.4
  */
 @Internal
diff --git a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/classic/AbstractHttpClientResponseHandler.java b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/classic/AbstractHttpClientResponseHandler.java
index 7076ec2f6..db1893683 100644
--- a/httpclient5/src/main/java/org/apache/hc/client5/http/impl/classic/AbstractHttpClientResponseHandler.java
+++ b/httpclient5/src/main/java/org/apache/hc/client5/http/impl/classic/AbstractHttpClientResponseHandler.java
@@ -49,6 +49,7 @@ import org.apache.hc.core5.http.io.entity.EntityUtils;
  * HttpClient may handle redirects (3xx responses) internally.
  * </p>
  *
+ * @param <T> the type of the value determined by the response.
  * @since 4.4
  */
 @Contract(threading = ThreadingBehavior.STATELESS)