fix 457 Support for Bearer Auth (#1930)

* fix #457 by introducing an HttpBearerAuth object

See https://github.com/OpenAPITools/openapi-generator/issues/457
Also https://github.com/OpenAPITools/openapi-generator/issues/1446 for typescript, https://github.com/OpenAPITools/openapi-generator/issues/1577 for python

Specs defined as follows currently generate BasicAuth and send an "Authorization: Basic [base64Encode(username + ":" + password)]" header
    components:
      securitySchemes:
        bearer:
          type: http
          scheme: bearer

This change will generate code which uses a new HttpBearerAuth class, which will send a "Authorization: [scheme] [accessToken]" header.
This change is slightly larger and more impactful than simply using OAuth for bearerBearer, but it allows for scheme values other than bearer.

This fix was enabled by the recent commit of 80ca67cfda

This PR is an alternative to https://github.com/OpenAPITools/openapi-generator/pull/1972

* update petstore samples

* Update HttpBearerAuth mustache templates and samples

* correct the expected number of generated java client files

* update the retrofit2 HttpBearerAuth template and samples

* Add resttemplate-specific HttpBearerAuth mustache and samples

* add vertx-specific HttpBearerAuth template and samples

* add java webclient-specific HttpBearerAuth template and samples

samples/client/petstore/java/resttemplate-withXml/src/main/java/org/openapitools/client/auth/HttpBearerAuth.java

@@ -0,0 +1,38 @@
+package org.openapitools.client.auth;
+
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.Base64Utils;
+import org.springframework.util.MultiValueMap;
+
+
+public class HttpBearerAuth implements Authentication {
+    private final String scheme;
+    private String bearerToken;
+
+    public HttpBearerAuth(String scheme) {
+        this.scheme = scheme;
+    }
+
+    public String getBearerToken() {
+        return bearerToken;
+    }
+
+    public void setBearerToken(String bearerToken) {
+        this.bearerToken = bearerToken;
+    }
+
+    @Override
+    public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams) {
+        if (bearerToken == null) {
+            return;
+        }
+        headerParams.add(HttpHeaders.AUTHORIZATION, (scheme != null ? upperCaseBearer(scheme) + " " : "") + bearerToken);
+    }
+
+    private static String upperCaseBearer(String scheme) {
+        return ("bearer".equalsIgnoreCase(scheme)) ? "Bearer" : scheme;
+    }
+}