Fix FormidableLabs#734 customHeaders is not taken into account

As per the documentation android custom Headers should pass as `customHeaders` but in module it was accessed as `headers`

Author: el173

android/src/main/java/com/rnappauth/RNAppAuthModule.java

@@ -94,15 +94,15 @@ public void prefetchConfiguration(
             final ReadableArray scopes,
             final ReadableMap serviceConfiguration,
             final boolean dangerouslyAllowInsecureHttpRequests,
-            final ReadableMap headers,
+            final ReadableMap customHeaders,
             final Double connectionTimeoutMillis,
             final Promise promise
     ) {
         if (warmAndPrefetchChrome) {
             warmChromeCustomTab(reactContext, issuer);
         }
 
-        this.parseHeaderMap(headers);
+        this.parseHeaderMap(customHeaders);
         final ConnectionBuilder builder = createConnectionBuilder(dangerouslyAllowInsecureHttpRequests, this.authorizationRequestHeaders, connectionTimeoutMillis);
         final CountDownLatch fetchConfigurationLatch = new CountDownLatch(1);
 
@@ -159,10 +159,10 @@ public void register(
             final ReadableMap serviceConfiguration,
             final Double connectionTimeoutMillis,
             final boolean dangerouslyAllowInsecureHttpRequests,
-            final ReadableMap headers,
+            final ReadableMap customHeaders,
             final Promise promise
     ) {
-        this.parseHeaderMap(headers);
+        this.parseHeaderMap(customHeaders);
         final ConnectionBuilder builder = createConnectionBuilder(dangerouslyAllowInsecureHttpRequests, this.registrationRequestHeaders, connectionTimeoutMillis);
         final AppAuthConfiguration appAuthConfiguration = this.createAppAuthConfiguration(builder, dangerouslyAllowInsecureHttpRequests);
         final HashMap<String, String> additionalParametersMap = MapUtil.readableMapToHashMap(additionalParameters);
@@ -232,10 +232,10 @@ public void authorize(
             final Boolean usePKCE,
             final String clientAuthMethod,
             final boolean dangerouslyAllowInsecureHttpRequests,
-            final ReadableMap headers,
+            final ReadableMap customHeaders,
             final Promise promise
     ) {
-        this.parseHeaderMap(headers);
+        this.parseHeaderMap(customHeaders);
         final ConnectionBuilder builder = createConnectionBuilder(dangerouslyAllowInsecureHttpRequests, this.authorizationRequestHeaders, connectionTimeoutMillis);
         final AppAuthConfiguration appAuthConfiguration = this.createAppAuthConfiguration(builder, dangerouslyAllowInsecureHttpRequests);
         final HashMap<String, String> additionalParametersMap = MapUtil.readableMapToHashMap(additionalParameters);
@@ -324,10 +324,10 @@ public void refresh(
             final Double connectionTimeoutMillis,
             final String clientAuthMethod,
             final boolean dangerouslyAllowInsecureHttpRequests,
-            final ReadableMap headers,
+            final ReadableMap customHeaders,
             final Promise promise
     ) {
-        this.parseHeaderMap(headers);
+        this.parseHeaderMap(customHeaders);
         final ConnectionBuilder builder = createConnectionBuilder(dangerouslyAllowInsecureHttpRequests, this.tokenRequestHeaders, connectionTimeoutMillis);
         final AppAuthConfiguration appAuthConfiguration = createAppAuthConfiguration(builder, dangerouslyAllowInsecureHttpRequests);
         final HashMap<String, String> additionalParametersMap = MapUtil.readableMapToHashMap(additionalParameters);