Add support of HTTP basic and API key auth to Java codegen

modules/swagger-codegen/src/main/resources/Java/auth/HttpBasicAuth.mustache

@@ -0,0 +1,36 @@
+package {{invokerPackage}}.auth;
+
+import java.util.Map;
+
+import java.io.UnsupportedEncodingException;
+import javax.xml.bind.DatatypeConverter;
+
+public class HttpBasicAuth implements Authentication {
+  private String username;
+  private String password;
+
+  public String getUsername() {
+    return username;
+  }
+
+  public void setUsername(String username) {
+    this.username = username;
+  }
+
+  public String getPassword() {
+    return password;
+  }
+
+  public void setPassword(String password) {
+    this.password = password;
+  }
+
+  @Override
+  public void processParams(Map<String, String> queryParams, Map<String, String> headerParams) {
+    try {
+      headerParams.put("Authorization", "Basic " + DatatypeConverter.printBase64Binary((username + ":" + password).getBytes("UTF-8")));
+    } catch (UnsupportedEncodingException e) {
+      throw new RuntimeException(e);
+    }
+  }
+}