add headers after construction

Author: rjernst

server/src/main/java/org/elasticsearch/ElasticsearchException.java

@@ -131,7 +131,6 @@ public class ElasticsearchException extends RuntimeException implements ToXConte
     @SuppressWarnings("this-escape")
     public ElasticsearchException(Throwable cause) {
         super(cause);
-        addErrorHeaders();
     }
 
     /**
@@ -146,7 +145,6 @@ public ElasticsearchException(Throwable cause) {
     @SuppressWarnings("this-escape")
     public ElasticsearchException(String msg, Object... args) {
         super(LoggerMessageFormat.format(msg, args));
-        addErrorHeaders();
     }
 
     /**
@@ -163,7 +161,6 @@ public ElasticsearchException(String msg, Object... args) {
     @SuppressWarnings("this-escape")
     public ElasticsearchException(String msg, Throwable cause, Object... args) {
         super(LoggerMessageFormat.format(msg, args), cause);
-        addErrorHeaders();
     }
 
     @SuppressWarnings("this-escape")
@@ -174,16 +171,18 @@ public ElasticsearchException(StreamInput in) throws IOException {
         metadata.putAll(in.readMapOfLists(StreamInput::readString));
     }
 
-    private void addErrorHeaders() {
-        if (isTimeout()) {
+    private void maybeAddErrorHeaders() {
+        if (isTimeout() && headers.containsKey(TIMED_OUT_HEADER) == false) {
             // see https://www.rfc-editor.org/rfc/rfc8941.html#section-4.1.9 for booleans in structured headers
             headers.put(TIMED_OUT_HEADER, List.of("?1"));
         }
-        // TODO: cache unwrapping the cause? we do this in several places...
-        Throwable cause = unwrapCause();
-        RestStatus status = ExceptionsHelper.status(cause);
-        if (status.getStatus() >= 500) {
-            headers.put(EXCEPTION_TYPE_HEADER, List.of(cause.getClass().getSimpleName()));
+        if (headers.containsKey(EXCEPTION_TYPE_HEADER) == false) {
+            // TODO: cache unwrapping the cause? we do this in several places...
+            Throwable cause = unwrapCause();
+            RestStatus status = ExceptionsHelper.status(cause);
+            if (status.getStatus() >= 500) {
+                headers.put(EXCEPTION_TYPE_HEADER, List.of(cause.getClass().getSimpleName()));
+            }
         }
     }
 
@@ -250,6 +249,7 @@ public void addHeader(String key, String... value) {
      * Returns a set of all header keys on this exception
      */
     public Set<String> getHeaderKeys() {
+        maybeAddErrorHeaders();
         return headers.keySet();
     }
 
@@ -258,10 +258,12 @@ public Set<String> getHeaderKeys() {
      * given key exists.
      */
     public List<String> getHeader(String key) {
+        maybeAddErrorHeaders();
         return headers.get(key);
     }
 
     protected Map<String, List<String>> getHeaders() {
+        maybeAddErrorHeaders();
         return headers;
     }
 
@@ -342,7 +344,7 @@ private static Writer<Throwable> createNestingFunction(int thisLevel, Runnable n
     protected void writeTo(StreamOutput out, Writer<Throwable> nestedExceptionsWriter) throws IOException {
         out.writeOptionalString(this.getMessage());
         nestedExceptionsWriter.write(out, this);
-        out.writeMap(headers, StreamOutput::writeStringCollection);
+        out.writeMap(getHeaders(), StreamOutput::writeStringCollection);
         out.writeMap(metadata, StreamOutput::writeStringCollection);
     }
 
@@ -391,7 +393,7 @@ protected XContentBuilder toXContent(XContentBuilder builder, Params params, int
         if (ex != this) {
             generateThrowableXContent(builder, params, this, nestedLevel);
         } else {
-            innerToXContent(builder, params, this, headers, metadata, getCause(), nestedLevel);
+            innerToXContent(builder, params, this, getHeaders(), metadata, getCause(), nestedLevel);
         }
         return builder;
     }