Remove unecessary Jackson dependency in trace filter

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/trace/WebRequestTraceFilter.java

@@ -37,9 +37,6 @@ import org.springframework.web.context.request.RequestAttributes;
 import org.springframework.web.context.request.ServletRequestAttributes;
 import org.springframework.web.filter.OncePerRequestFilter;
 
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
-
 /**
  * Servlet {@link Filter} that logs all requests to a {@link TraceRepository}.
  *
@@ -55,8 +52,6 @@ public class WebRequestTraceFilter extends OncePerRequestFilter implements Order
 
 	private final TraceRepository traceRepository;
 
-	private final ObjectMapper objectMapper = new ObjectMapper();
-
 	private ErrorAttributes errorAttributes;
 
 	/**
@@ -93,16 +88,9 @@ public class WebRequestTraceFilter extends OncePerRequestFilter implements Order
 			this.logger.trace("Processing request " + request.getMethod() + " "
 					+ request.getRequestURI());
 			if (this.dumpRequests) {
-				try {
-					@SuppressWarnings("unchecked")
-					Map<String, Object> headers = (Map<String, Object>) trace
-							.get("headers");
-					this.logger.trace("Headers: "
-							+ this.objectMapper.writeValueAsString(headers));
-				}
-				catch (JsonProcessingException ex) {
-					throw new IllegalStateException("Cannot create JSON", ex);
-				}
+				@SuppressWarnings("unchecked")
+				Map<String, Object> headers = (Map<String, Object>) trace.get("headers");
+				this.logger.trace("Headers: " + headers);
 			}
 		}