Adding order for TraceFilter; fixes gh-1020

docs/src/main/asciidoc/spring-cloud-sleuth.adoc

@@ -438,6 +438,9 @@ add to the Span a tag with key `custom` and a value `tag`.
 include::../../../..//spring-cloud-sleuth-core/src/test/java/org/springframework/cloud/sleuth/instrument/web/TraceFilterIntegrationTests.java[tags=response_headers,indent=0]
 ----
 
+To change the order of `TraceFilter` registration, please set the
+`spring.sleuth.web.filter-order` property.
+
 === Custom SA tag in Zipkin
 
 Sometimes you want to create a manual Span that will wrap a call to an external service which is not instrumented.

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/SleuthWebProperties.java

@@ -25,6 +25,12 @@ public class SleuthWebProperties {
 	 */
 	private String skipPattern = DEFAULT_SKIP_PATTERN;
 
+	/**
+	 * Order in which the {@link TraceFilter} should be registered.
+	 * Defaults to {@link TraceFilter#ORDER}
+	 */
+	private int filterOrder = TraceFilter.ORDER;
+
 	private Client client;
 
 	public boolean isEnabled() {
@@ -43,6 +49,18 @@ public class SleuthWebProperties {
 		this.skipPattern = skipPattern;
 	}
 
+	public static String getDefaultSkipPattern() {
+		return DEFAULT_SKIP_PATTERN;
+	}
+
+	public int getFilterOrder() {
+		return this.filterOrder;
+	}
+
+	public void setFilterOrder(int filterOrder) {
+		this.filterOrder = filterOrder;
+	}
+
 	public Client getClient() {
 		return this.client;
 	}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/web/TraceWebAutoConfiguration.java

@@ -89,12 +89,12 @@ public class TraceWebAutoConfiguration {
 	}
 
 	@Bean
-	public FilterRegistrationBean traceWebFilter(TraceFilter traceFilter) {
+	public FilterRegistrationBean traceWebFilter(TraceFilter traceFilter, SleuthWebProperties sleuthWebProperties) {
 		FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(
 				traceFilter);
 		filterRegistrationBean.setDispatcherTypes(ASYNC, ERROR, FORWARD, INCLUDE,
 				REQUEST);
-		filterRegistrationBean.setOrder(TraceFilter.ORDER);
+		filterRegistrationBean.setOrder(sleuthWebProperties.getFilterOrder());
 		return filterRegistrationBean;
 	}