Adding back some missing code

notification-core/src/main/java/org/opengroup/osdu/notification/utils/NotificationFilter.java

+// Copyright © 2020 Amazon Web Services
+// Copyright 2017-2019, Schlumberger
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package org.opengroup.osdu.notification.utils;
+
+import org.opengroup.osdu.core.common.http.ResponseHeadersFactory;
+import org.opengroup.osdu.core.common.model.http.DpsHeaders;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Component;
+
+import javax.inject.Inject;
+import javax.servlet.*;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.util.Map;
+
+
+@Component
+public class NotificationFilter implements Filter {
+
+	@Inject
+	private DpsHeaders dpsHeaders;
+
+	private ResponseHeadersFactory responseHeadersFactory = new ResponseHeadersFactory();
+
+	// defaults to * for any front-end, string must be comma-delimited if more than one domain
+	@Value("${ACCESS_CONTROL_ALLOW_ORIGIN_DOMAINS:*}")
+	String ACCESS_CONTROL_ALLOW_ORIGIN_DOMAINS;
+
+	@Override
+	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
+			throws IOException, ServletException {
+		chain.doFilter(request, response);
+
+		HttpServletResponse httpResponse = (HttpServletResponse) response;
+
+		this.dpsHeaders.addCorrelationIdIfMissing();
+
+		Map<String, String> responseHeaders = responseHeadersFactory.getResponseHeaders(ACCESS_CONTROL_ALLOW_ORIGIN_DOMAINS);
+		for (Map.Entry<String, String> header : responseHeaders.entrySet()) {
+			httpResponse.setHeader(header.getKey(), header.getValue());
+		}
+		httpResponse.addHeader(DpsHeaders.CORRELATION_ID, this.dpsHeaders.getCorrelationId());
+	}
+
+	@Override
+	public void destroy() {
+	}
+}