Fix crash on escaped type in erlang-server handler (#20735)

Author: kpy3

modules/openapi-generator/src/main/resources/erlang-server/handler.mustache

@@ -91,7 +91,7 @@ is_authorized(Req, State) ->
     {{#consumes.size}}
     {[
     {{#consumes}}
-      {<<"{{mediaType}}">>, handle_type_accepted}{{^-last}}{{#consumes.size}},{{/consumes.size}}{{/-last}}
+      {<<"{{{mediaType}}}">>, handle_type_accepted}{{^-last}}{{#consumes.size}},{{/consumes.size}}{{/-last}}
     {{/consumes}}
      ], Req, State};
     {{/consumes.size}}
@@ -114,7 +114,7 @@ is_authorized(Req, State) ->
     {{#produces.size}}
     {[
     {{#produces}}
-      {<<"{{mediaType}}">>, handle_type_provided}{{^-last}}{{#produces.size}},{{/produces.size}}{{/-last}}
+      {<<"{{{mediaType}}}">>, handle_type_provided}{{^-last}}{{#produces.size}},{{/produces.size}}{{/-last}}
     {{/produces}}
      ], Req, State};
     {{/produces.size}}

modules/openapi-generator/src/test/java/org/openapitools/codegen/erlang/ErlangServerCodegenTest.java

@@ -0,0 +1,39 @@
+package org.openapitools.codegen.erlang;
+
+import org.openapitools.codegen.ClientOptInput;
+import org.openapitools.codegen.DefaultGenerator;
+import org.openapitools.codegen.config.CodegenConfigurator;
+import org.testng.annotations.Test;
+
+import java.io.File;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.openapitools.codegen.TestUtils.newTempFolder;
+
+public class ErlangServerCodegenTest {
+
+    @Test
+    public void testCharsetInContentTypeCorrectlyEncodedForErlangServer() {
+        final Path output = newTempFolder();
+        final CodegenConfigurator configurator = new CodegenConfigurator()
+                .setGeneratorName("erlang-server")
+                .setInputSpec("src/test/resources/3_0/issue_19895.yaml")
+                .setOutputDir(output.toString().replace("\\", "/"));
+
+        final ClientOptInput clientOptInput = configurator.toClientOptInput();
+        DefaultGenerator generator = new DefaultGenerator();
+        List<File> files = generator.opts(clientOptInput).generate();
+
+        var defaultApiFile = output.resolve("src/openapi_default_handler.erl");
+        assertThat(files).contains(defaultApiFile.toFile());
+        assertThat(defaultApiFile).content()
+                .doesNotContain(
+                        "application/json;charset&#x3D;utf-8")
+                .contains(
+                        "application/json;charset=utf-8"
+                );
+    }
+
+}