docs(feign): add detailed javadoc for RequestLine annotation parameters

core/src/main/java/feign/RequestLine.java

@@ -30,9 +30,65 @@
 @Retention(RUNTIME)
 public @interface RequestLine {
 
+  /**
+   * The HTTP request line, including the method and an optional URI template.
+   *
+   * <p>The string must begin with a valid {@linkplain feign.Request.HttpMethod HTTP method name}
+   * (e.g. {@linkplain feign.Request.HttpMethod#GET GET}, {@linkplain feign.Request.HttpMethod#POST
+   * POST}, {@linkplain feign.Request.HttpMethod#PUT PUT}), followed by a space and a URI template.
+   * If only the HTTP method is specified (e.g. {@code "DELETE"}), the request will use the base URL
+   * defined for the client.
+   *
+   * <p>Example:
+   *
+   * <pre>{@code @RequestLine("GET /repos/{owner}/{repo}")
+   * Repo getRepo(@Param("owner") String owner, @Param("repo") String repo);
+   * }</pre>
+   *
+   * @return the HTTP method and optional URI template for the request.
+   * @see feign.template.UriTemplate
+   */
   String value();
 
+  /**
+   * Controls whether percent-encoded forward slashes ({@code %2F}) in expanded path variables are
+   * decoded back to {@code '/'} before sending the request.
+   *
+   * <p>When {@code true} (the default), any {@code %2F} sequences produced during URI template
+   * expansion will be replaced with literal slashes, meaning that path variables containing slashes
+   * will be interpreted as multiple path segments.
+   *
+   * <p>When {@code false}, percent-encoded slashes ({@code %2F}) are preserved in the final URL.
+   * This is useful when a path variable intentionally includes a slash as part of its value (for
+   * example, an encoded identifier such as {@code "foo%2Fbar"}).
+   *
+   * <p>Example:
+   *
+   * <pre>{@code @RequestLine(value = "GET /projects/{id}", decodeSlash = false)
+   * Project getProject(@Param("id") String encodedId);
+   * }</pre>
+   *
+   * @return {@code true} if encoded slashes should be decoded (default behavior); {@code false} to
+   *     preserve {@code %2F} sequences in the URL.
+   */
   boolean decodeSlash() default true;
 
+  /**
+   * Specifies how collections (e.g. {@link java.util.List List} or arrays) are serialized when
+   * expanded into the URI template.
+   *
+   * <p>Determines whether values are represented as exploded parameters (repeated keys) or as a
+   * single comma-separated value, depending on the chosen {@link feign.CollectionFormat}.
+   *
+   * <p>Example:
+   *
+   * <ul>
+   *   <li>{@linkplain CollectionFormat#EXPLODED EXPLODED}: {@code /items?id=1&id=2&id=3}
+   *   <li>{@linkplain CollectionFormat#CSV CSV}: {@code /items?id=1,2,3}
+   * </ul>
+   *
+   * @return the collection serialization format to use when expanding templates.
+   * @see CollectionFormat
+   */
   CollectionFormat collectionFormat() default CollectionFormat.EXPLODED;
 }