refactor: make API-Version response header configurable

It is disabled by default.

Author: stempler

deegree-ogcapi-features/src/main/java/org/deegree/services/oaf/filter/ApiVersionResponseFilter.java

@@ -29,6 +29,7 @@
 import javax.ws.rs.container.ContainerResponseFilter;
 import javax.ws.rs.ext.Provider;
 
+import org.deegree.commons.utils.TunableParameter;
 import org.deegree.services.oaf.openapi.OpenApiCreator;
 
 
@@ -40,18 +41,24 @@
 @Provider
 public class ApiVersionResponseFilter implements ContainerResponseFilter {
 
-	// Whether to add API version to the header or not
-	private boolean addApiVersionToHeader = true;
+	/**
+	 * Name for parameter that allows enabling returning the API version as response header. 
+	 */
+	public static final String PARAMETER_ENABLE_VERSION_HEADER = "deegree.oaf.openapi.version_response_header";
+	
+	private boolean addApiVersionToHeader = TunableParameter.get(PARAMETER_ENABLE_VERSION_HEADER, false);
 
-	// Constant for API-Version
-	private static final String API_VERSION_CONSTANT = "API-Version";
+	/**
+	 * Name for response header with API version.
+	 */
+	public static final String HEADER_API_VERSION = "API-Version";
 
 	@Override
 	public void filter(ContainerRequestContext requestContext, ContainerResponseContext responseContext)
 			throws IOException {
 
 		if (addApiVersionToHeader) {
-			responseContext.getHeaders().add(API_VERSION_CONSTANT, OpenApiCreator.VERSION);
+			responseContext.getHeaders().add(HEADER_API_VERSION, OpenApiCreator.VERSION);
 		}
 	}