Minlopro: added PKCE helper class to manage PKCE state

src/minlopro/main/classes/auth-provider-plugin-web-server-with-PKCE/PKCE.cls

@@ -0,0 +1,31 @@
+public without sharing class PKCE {
+    private final static String INSTANCE_URL = '@SF_INSTANCE_URL';
+    private final static String PKCE_ENDPOINT = '/services/oauth2/pkce/generator'; // Public PKCE endpoint;
+    private final static Cache.OrgPartition PARTITION = Cache.Org.getPartition('local.PKCE'); // Org Cache;
+
+    static {
+        Assert.isNotNull(PARTITION, 'PKCE Org Cache Partition is not defined!');
+    }
+
+    public State generate(String cacheKey) {
+        // Step 1 - Invoke public Salesforce endpoint to get PKCE state;
+        HttpRequest pkceRequest = new HttpRequest();
+        pkceRequest.setMethod('GET');
+        pkceRequest.setEndpoint(String.format('{0}/{1}', Lists.of(INSTANCE_URL, PKCE_ENDPOINT)));
+        HttpResponse pkceResponse = new Http().send(pkceRequest);
+        State pkceState = (State) JSON.deserialize(pkceResponse.getBody(), State.class);
+        // Step 2 - Save state in Platform Cache;
+        PARTITION.put(cacheKey, pkceState, 300);
+        return pkceState;
+    }
+
+    public State get(String cacheKey) {
+        return (State) PARTITION.get(cacheKey);
+    }
+
+    public class State {
+        public String code_challenge_method = 'S256';
+        public String code_challenge = null; // e.g. JB7nT*************
+        public String code_verifier = null; // e.g. GkLvw**************
+    }
+}

src/minlopro/main/classes/auth-provider-plugin-web-server-with-PKCE/PKCE.cls-meta.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
+    <apiVersion>61.0</apiVersion>
+    <status>Active</status>
+</ApexClass>