Merge pull request #53 from mdemille/master

Add an encode method that accepts a `Supplier<Header>` so any Header class can be provided

src/main/java/io/fusionauth/jwt/JWTEncoder.java

@@ -25,6 +25,7 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.function.Consumer;
+import java.util.function.Supplier;
 
 /**
  * @author Daniel DeGroff
@@ -41,6 +42,24 @@ public String encode(JWT jwt, Signer signer) {
     return encode(jwt, signer, h -> h.set("kid", signer.getKid()));
   }
 
+  /**
+   * Encode the JWT to produce a dot separated encoded string that can be sent in an HTTP request header.
+   *
+   * @param jwt      The JWT.
+   * @param signer   The signer used to add a signature to the JWT.
+   * @param supplier A header supplier to optionally add header values to the encoded JWT. May be null.
+   * @return the encoded JWT string.
+   */
+  public String encode(JWT jwt, Signer signer, Supplier<Header> supplier) {
+    final Header header;
+    if (supplier != null) {
+      header = supplier.get();
+    } else {
+      header = new Header();
+    }
+    return encode(jwt, signer, header);
+  }
+
   /**
    * Encode the JWT to produce a dot separated encoded string that can be sent in an HTTP request header.
    *
@@ -50,14 +69,18 @@ public String encode(JWT jwt, Signer signer) {
    * @return the encoded JWT string.
    */
   public String encode(JWT jwt, Signer signer, Consumer<Header> consumer) {
-    Objects.requireNonNull(jwt);
-    Objects.requireNonNull(signer);
-
-    List<String> parts = new ArrayList<>(3);
     Header header = new Header();
     if (consumer != null) {
       consumer.accept(header);
     }
+    return encode(jwt, signer, header);
+  }
+
+  private String encode(JWT jwt, Signer signer, Header header) {
+    Objects.requireNonNull(jwt);
+    Objects.requireNonNull(signer);
+
+    List<String> parts = new ArrayList<>(3);
     // Set this after we pass the header to the consumer to ensure it isn't tampered with, only the signer can set the algorithm.
     header.algorithm = signer.getAlgorithm();
     parts.add(base64Encode(Mapper.serialize(header)));

src/test/java/io/fusionauth/jwt/JWTTest.java

@@ -563,9 +563,12 @@ public void test_complexPayload() {
     Signer signer = HMACSigner.newSHA256Signer("secret");
     Verifier verifier = HMACVerifier.newVerifier("secret");
 
-    String encodedJWT = JWT.getEncoder().encode(expectedJWT, signer, header -> header
-        .set("gty", Collections.singletonList("client_credentials"))
-        .set("kid", "1234"));
+    String encodedJWT = JWT.getEncoder().encode(expectedJWT, signer, () -> {
+      final Header header = new Header();
+      header.set("gty", Collections.singletonList("client_credentials"));
+      header.set("kid", "1234");
+      return header;
+    });
     JWT actualJwt = JWT.getDecoder().decode(encodedJWT, verifier);
 
     assertEquals(actualJwt.header.algorithm, Algorithm.HS256);