Do not encode span context in HTTP_HEADERS format (#721)

We know that string representation of a span context is safe to use in
HTTP header. Thus, there is no need to encode it. JS & Go clients
already avoid that unnecesserary encoding. This change is backward
compatible because all clients unencode span context even if they do not
encode it. More pragmatically, a client impacted by this change would
already be incompatible with JS & Go clients.

Signed-off-by: Clément MATHIEU <clement@unportant.info>

Author: cykl

jaeger-core/src/main/java/io/jaegertracing/internal/propagation/TextMapCodec.java

@@ -126,7 +126,7 @@ public static String contextAsString(JaegerSpanContext context) {
 
   @Override
   public void inject(JaegerSpanContext spanContext, TextMap carrier) {
-    carrier.put(contextKey, encodedValue(contextAsString(spanContext)));
+    carrier.put(contextKey, contextAsString(spanContext));
     for (Map.Entry<String, String> entry : spanContext.baggageItems()) {
       carrier.put(keys.prefixedKey(entry.getKey(), baggagePrefix), encodedValue(entry.getValue()));
     }

jaeger-core/src/test/java/io/jaegertracing/internal/propagation/TextMapCodecTest.java

@@ -158,4 +158,45 @@ public void testAdhocBaggageWithoutTraceId() {
     assertEquals("v2", context.getBaggageItem("k2"));
     assertEquals(null, context.getBaggageItem("k3"));
   }
+
+  @Test
+  public void testInjectDoNotEncodeSpanContext() {
+    TextMapCodec codec = new TextMapCodec(true);
+    Map<String, String> headers = new HashMap<String, String>();
+    long traceIdLow = 42;
+    long spanId = 1;
+    long parentId = 0;
+    codec.inject(new JaegerSpanContext(0L, traceIdLow, spanId, parentId, (byte)1), new TextMapAdapter(headers));
+
+    String traceId = headers.get("uber-trace-id");
+    assertEquals("2a:1:0:1", traceId);
+  }
+
+  @Test
+  public void testExtractSupportNonEncodedSpanContext() {
+    Map<String, String> headers = new HashMap<String, String>();
+    headers.put("uber-trace-id", "2a:1:0:1");
+
+    TextMapCodec codec = new TextMapCodec(true);
+    JaegerSpanContext context = codec.extract(new TextMapAdapter(headers));
+
+    assertEquals(42, context.getTraceIdLow());
+    assertEquals(0L, context.getTraceIdHigh());
+    assertEquals(1L, context.getSpanId());
+    assertTrue(context.isSampled());
+  }
+
+  @Test
+  public void testExtractSupportEncodedSpanContext() {
+    Map<String, String> headers = new HashMap<String, String>();
+    headers.put("uber-trace-id", "2a%3A1%3A0%3A1");
+
+    TextMapCodec codec = new TextMapCodec(true);
+    JaegerSpanContext context = codec.extract(new TextMapAdapter(headers));
+
+    assertEquals(42, context.getTraceIdLow());
+    assertEquals(0L, context.getTraceIdHigh());
+    assertEquals(1L, context.getSpanId());
+    assertTrue(context.isSampled());
+  }
 }