feat(CloudPakForDataServiceInstanceAuthenticator): add new cp4d service instance authenticator (#156)

This commit introduces a new authenticator implementation that supports the
 "GET /v3/service_instances/{service_instance_id}/token"
operation which is part of the Cloud Pak For Data authentication service. This allows users to obtain
access tokens for service instances using the username, apikey, and service instance id in CP4D.

Author: jpfloresibm

.secrets.baseline

@@ -3,7 +3,7 @@
     "files": "package-lock.json|^.secrets.baseline$",
     "lines": null
   },
-  "generated_at": "2021-10-25T15:49:19Z",
+  "generated_at": "2021-11-17T14:53:46Z",
   "plugins_used": [
     {
       "name": "AWSKeyDetector"
@@ -104,23 +104,23 @@
         "hashed_secret": "d4c3d66fd0c38547a3c7a4c6bdc29c36911bc030",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 44,
+        "line_number": 45,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "8318df9ecda039deac9868adf1944a29a95c7114",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 46,
+        "line_number": 48,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "9a66213cc16d178fdbf9f4da6b7bd92497fda404",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 52,
+        "line_number": 54,
         "type": "Secret Keyword",
         "verified_result": null
       }
@@ -173,6 +173,16 @@
         "verified_result": null
       }
     ],
+    "src/test/java/com/ibm/cloud/sdk/core/test/security/Cp4dServiceInstanceAuthenticatorTest.java": [
+      {
+        "hashed_secret": "2207d3f3ac68743290fe4affc71c10bec4962232",
+        "is_secret": false,
+        "is_verified": false,
+        "line_number": 61,
+        "type": "Secret Keyword",
+        "verified_result": null
+      }
+    ],
     "src/test/java/com/ibm/cloud/sdk/core/test/security/JsonWebTokenTest.java": [
       {
         "hashed_secret": "c6ba9cef42f298486a61546fefd03a4177e60a99",
@@ -201,6 +211,16 @@
         "verified_result": null
       }
     ],
+    "src/test/resources/cp4d_service_instance_token.json": [
+      {
+        "hashed_secret": "0cadf54eaba861bbe38dadf15ceaa37a98ba68bb",
+        "is_secret": false,
+        "is_verified": false,
+        "line_number": 4,
+        "type": "JSON Web Token",
+        "verified_result": null
+      }
+    ],
     "src/test/resources/cp4d_token.json": [
       {
         "hashed_secret": "0cadf54eaba861bbe38dadf15ceaa37a98ba68bb",
@@ -261,6 +281,16 @@
         "verified_result": null
       }
     ],
+    "src/test/resources/refreshed_cp4d_service_instance_token.json": [
+      {
+        "hashed_secret": "78afb9234e91232b50987dd260c09e47eeefc2f5",
+        "is_secret": false,
+        "is_verified": false,
+        "line_number": 4,
+        "type": "JSON Web Token",
+        "verified_result": null
+      }
+    ],
     "src/test/resources/refreshed_cp4d_token.json": [
       {
         "hashed_secret": "78afb9234e91232b50987dd260c09e47eeefc2f5",

src/main/java/com/ibm/cloud/sdk/core/security/Authenticator.java

@@ -28,6 +28,7 @@ public interface Authenticator {
   String AUTHTYPE_IAM = "iam";
   String AUTHTYPE_CP4D = "cp4d";
   String AUTHTYPE_CP4D_SERVICE = "cp4dService";
+  String AUTHTYPE_CP4D_SERVICE_INSTANCE = "cp4dServiceInstance";
   String AUTHTYPE_BEARER_TOKEN = "bearerToken";
   String AUTHTYPE_CONTAINER = "container";
   String AUTHTYPE_VPC = "vpc";
@@ -42,6 +43,7 @@ public interface Authenticator {
   String PROPNAME_URL = "AUTH_URL";
   String PROPNAME_DISABLE_SSL = "AUTH_DISABLE_SSL";
   String PROPNAME_APIKEY = "APIKEY";
+  String PROPNAME_SERVICE_INSTANCE_ID = "SERVICE_INSTANCE_ID";
   String PROPNAME_CLIENT_ID = "CLIENT_ID";
   String PROPNAME_CLIENT_SECRET = "CLIENT_SECRET";
   String PROPNAME_SCOPE = "SCOPE";