Addressed feedback

application/src/main/java/net/corda/v5/application/crypto/SigningService.java

@@ -49,10 +49,7 @@ public interface SigningService {
      * primary identity, or previously generated via the freshKey method. If the {@link PublicKey} is actually
      * a {@link CompositeKey}, the first leaf signing key hosted by the node is used.
      * @param signatureSpec The {@link SignatureSpec} to use when producing this signature.
-     * @param context The execution context of the signing operation as a map of strings. Currently accepts the following parameters
-     * <ul>
-     *   <li>category: the type of signing key requested for additional verification</li>
-     * </ul>
+     * @param context The execution context of the signing operation.
      *
      * @return A {@link DigitalSignature.WithKeyId} representing the signed data and the {@link PublicKey} that belongs to the
      * same {@link KeyPair} as the {@link PrivateKey} that signed the data.
@@ -61,7 +58,7 @@ public interface SigningService {
      */
     @Suspendable
     @NotNull
-    DigitalSignature.WithKeyId sign(@NotNull byte[] bytes, @NotNull PublicKey publicKey, @NotNull SignatureSpec signatureSpec, @NotNull Map<String, String> context);
+    DigitalSignature.WithKeyId sign(@NotNull byte[] bytes, @NotNull PublicKey publicKey, @NotNull SignatureSpec signatureSpec, @NotNull SigningServiceSignContext context);
 
     /**
      * Looks into a set of signing keys to find keys owned by the caller. In case of {@link CompositeKey} it looks into

application/src/main/java/net/corda/v5/application/crypto/SigningServiceSignContext.java

@@ -0,0 +1,18 @@
+package net.corda.v5.application.crypto;
+
+import net.corda.v5.base.annotations.CordaSerializable;
+
+/*
+ * Context attached to the sign operation of SigningService
+ */
+@CordaSerializable
+public final class SigningServiceSignContext {
+    private final String keyCategory;
+
+    /**
+     * @param keyCategory the category of the key to be signed with
+     */
+    public SigningServiceSignContext(String keyCategory) {
+        this.keyCategory = keyCategory;
+    }
+}