feat: document_overrides quirk to patch invalid OIDD files

src/oidcc_provider_configuration.erl

@@ -34,7 +34,8 @@
 
 -type quirks() :: #{
     allow_issuer_mismatch => boolean(),
-    allow_unsafe_http => boolean()
+    allow_unsafe_http => boolean(),
+    document_overrides => map()
 }.
 %% Allow Specification Non-compliance
 %%
@@ -45,6 +46,8 @@
 %%     and function parameter</li>
 %%   <li>`allow_unsafe_http' - Allow unsafe HTTP. Use this for development
 %%     providers and <strong>never in production</strong>.</li>
+%%   <li>`document_overrides' - a map to merge with the real OIDD document,
+%%     in case the OP left out some values.</li>
 %% </ul>
 
 -type opts() :: #{
@@ -277,10 +280,13 @@ load_jwks(JwksUri, Opts) ->
 %% @since 3.1.0
 -spec decode_configuration(Configuration, Opts) -> {ok, t()} | {error, error()} when
     Configuration :: map(), Opts :: opts().
-decode_configuration(Configuration, Opts) ->
+decode_configuration(Configuration0, Opts) ->
     Quirks = maps:get(quirks, Opts, #{}),
     AllowUnsafeHttp = maps:get(allow_unsafe_http, Quirks, false),
 
+    DocumentOverrides = maps:get(document_overrides, Quirks, #{}),
+    Configuration = maps:merge(Configuration0, DocumentOverrides),
+
     maybe
         {ok, {
             #{

test/oidcc_provider_configuration_test.erl

@@ -576,6 +576,20 @@ allow_unsafe_http_quirk_test() ->
 
     ok.
 
+document_overrides_quirk_test() ->
+    PrivDir = code:priv_dir(oidcc),
+    {ok, Configuration} = file:read_file(PrivDir ++ "/test/fixtures/google-metadata.json"),
+
+    ?assertMatch(
+        {ok, #oidcc_provider_configuration{
+            issuer = <<"https://example.com">>
+        }},
+        oidcc_provider_configuration:decode_configuration(jose:decode(Configuration), #{
+            quirks => #{document_overrides => #{<<"issuer">> => <<"https://example.com">>}}
+        })
+    ),
+    ok.
+
 uri_concatenation_test() ->
     ok = meck:new(httpc, [no_link]),
     HttpFun =