Replace StringBuilder#append(String) with StringBuilder#append(char)

dd-java-agent/agent-crashtracking/src/main/java/com/datadog/crashtracking/parsers/HotspotCrashLogParser.java

@@ -157,7 +157,7 @@ public CrashLog parse(String crashLog) {
                 pid = line.substring(pidIdx + 4, endIdx);
               }
             } else {
-              message.append(line.substring(2)).append("\n");
+              message.append(line.substring(2)).append('\n');
             }
           }
           break;

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/agent/StringTemplateBuilder.java

@@ -56,7 +56,7 @@ public String evaluate(CapturedContext context, LogProbe.LogStatus status) {
             status.addError(new EvaluationError(ex.getExpr(), ex.getMessage()));
             String msg =
                 ex instanceof RedactedException ? Redaction.REDACTED_VALUE : ex.getMessage();
-            sb.append("{").append(msg).append("}");
+            sb.append('{').append(msg).append('}');
           }
           if (!status.getErrors().isEmpty()) {
             status.setLogTemplateErrors(true);

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/probe/ProbeDefinition.java

@@ -85,7 +85,7 @@ public String concatTags() {
     StringBuilder sb = new StringBuilder();
     for (Tag tag : tags) {
       if (sb.length() > 0) {
-        sb.append(",");
+        sb.append(',');
       }
       sb.append(tag);
     }

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/sink/IntakeBatchHelper.java

@@ -61,7 +61,7 @@ private static int buildPayloadBatch(
       List<String> payloads, int start, int count, StringBuilder sb) {
     int totalSize = 0;
     int elementCount = 0;
-    sb.append("[");
+    sb.append('[');
     for (int i = start; i < start + count; i++) {
       String jsonStr = payloads.get(i);
       totalSize += jsonStr.length();
@@ -71,13 +71,13 @@ private static int buildPayloadBatch(
         break;
       }
       sb.append(jsonStr);
-      sb.append(",");
+      sb.append(',');
       elementCount++;
     }
     if (elementCount > 0) {
       sb.delete(sb.lastIndexOf(","), sb.length());
     }
-    sb.append("]");
+    sb.append(']');
     return elementCount;
   }
 

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/util/StringTokenWriter.java

@@ -31,7 +31,7 @@ public StringTokenWriter(StringBuilder sb, List<EvaluationError> evalErrors) {
   @Override
   public void prologue(Object value, String type) {
     if (inMapEntry && !initial) {
-      sb.append("=");
+      sb.append('=');
     } else if (inCollection && !initial) {
       sb.append(", ");
     }
@@ -85,7 +85,7 @@ public void primitiveArrayElement(String value, String type) {
 
   @Override
   public void collectionPrologue(Object value) {
-    sb.append("[");
+    sb.append('[');
     initial = true;
     inCollection = true;
   }
@@ -98,7 +98,7 @@ public void collectionEpilogue(Object value, boolean isComplete, int size) {
 
   @Override
   public void mapPrologue(Object value) {
-    sb.append("{");
+    sb.append('{');
     initial = true;
     inCollection = true;
   }
@@ -108,14 +108,14 @@ public void mapEntryPrologue(Map.Entry<?, ?> entry) {
     if (!initial) {
       sb.append(", ");
     }
-    sb.append("[");
+    sb.append('[');
     initial = true;
     inMapEntry = true;
   }
 
   @Override
   public void mapEntryEpilogue(Map.Entry<?, ?> entry) {
-    sb.append("]");
+    sb.append(']');
     inMapEntry = false;
   }
 
@@ -127,7 +127,7 @@ public void mapEpilogue(boolean isComplete, int size) {
 
   @Override
   public void objectPrologue(Object value) {
-    sb.append("{");
+    sb.append('{');
     initial = true;
   }
 
@@ -137,12 +137,12 @@ public void objectFieldPrologue(String fieldName, Object value, int maxDepth) {
       sb.append(", ");
     }
     initial = false;
-    sb.append(fieldName).append("=");
+    sb.append(fieldName).append('=');
   }
 
   @Override
   public void objectEpilogue(Object value) {
-    sb.append("}");
+    sb.append('}');
   }
 
   @Override
@@ -167,16 +167,16 @@ public void notCaptured(SerializerWithLimits.NotCapturedReason reason) {
         sb.append("...");
         break;
       case TIMEOUT:
-        sb.append("{").append(TIMEOUT_REASON).append("}");
+        sb.append('{').append(TIMEOUT_REASON).append('}');
         break;
       case FIELD_COUNT:
         sb.append(", ...");
         break;
       case REDACTED_IDENT:
-        sb.append("{").append(REDACTED_IDENT_REASON).append("}");
+        sb.append('{').append(REDACTED_IDENT_REASON).append('}');
         break;
       case REDACTED_TYPE:
-        sb.append("{").append(REDACTED_TYPE_REASON).append("}");
+        sb.append('{').append(REDACTED_TYPE_REASON).append('}');
         break;
       default:
         throw new RuntimeException("Unsupported NotCapturedReason: " + reason);
@@ -185,6 +185,6 @@ public void notCaptured(SerializerWithLimits.NotCapturedReason reason) {
 
   @Override
   public void notCaptured(String reason) throws Exception {
-    sb.append("(Error: ").append(reason).append(")");
+    sb.append("(Error: ").append(reason).append(')');
   }
 }

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/sink/DebuggerSinkTest.java

@@ -322,7 +322,7 @@ public void splitDiagnosticsBatch() {
     DebuggerSink sink = createDebuggerSink(diagnosticUploader, false);
     StringBuilder largeMessageBuilder = new StringBuilder(100_001);
     for (int i = 0; i < 100_000; i++) {
-      largeMessageBuilder.append("f");
+      largeMessageBuilder.append('f');
     }
     String largeMessage = largeMessageBuilder.toString();
     for (int i = 0; i < 100; i++) {
@@ -342,7 +342,7 @@ public void splitDiagnosticsBatchDebuggerTrack() {
     DebuggerSink sink = createDebuggerSink(diagnosticUploader, true);
     StringBuilder largeMessageBuilder = new StringBuilder(100_001);
     for (int i = 0; i < 100_000; i++) {
-      largeMessageBuilder.append("f");
+      largeMessageBuilder.append('f');
     }
     String largeMessage = largeMessageBuilder.toString();
     for (int i = 0; i < 100; i++) {
@@ -362,7 +362,7 @@ public void tooLargeDiagnostic() {
     DebuggerSink sink = createDefaultDebuggerSink();
     StringBuilder tooLargeMessageBuilder = new StringBuilder(MAX_PAYLOAD + 1);
     for (int i = 0; i < MAX_PAYLOAD; i++) {
-      tooLargeMessageBuilder.append("f");
+      tooLargeMessageBuilder.append('f');
     }
     String tooLargeMessage = tooLargeMessageBuilder.toString();
     sink.getProbeDiagnosticsSink().addError(new ProbeId("1", 1), tooLargeMessage);

dd-java-agent/agent-debugger/src/test/java/com/datadog/debugger/util/CapturedValueAdapterTest.java

@@ -55,7 +55,7 @@ void collection() throws IOException {
     StringBuilder sb = new StringBuilder();
     for (int i = 0; i < 10; i++) {
       if (i > 0) {
-        sb.append(",");
+        sb.append(',');
       }
       sb.append(String.format(CAPTURED_VALUE_SIMPLE_TEMPLATE, int.class.getTypeName(), i));
     }
@@ -66,7 +66,7 @@ void collection() throws IOException {
     sb = new StringBuilder();
     for (int i = 0; i < 10; i++) {
       if (i > 0) {
-        sb.append(",");
+        sb.append(',');
       }
       sb.append(
           String.format(CAPTURED_VALUE_SIMPLE_TEMPLATE, String.class.getTypeName(), "foo" + i));

dd-java-agent/agent-logging/src/main/java/datadog/trace/logging/simplelogger/SLCompatHelper.java

@@ -108,12 +108,12 @@ private void embedException(StringBuilder buf, Throwable t) {
     if (t != null) {
       buf.append(" [exception:");
       buf.append(t.toString());
-      buf.append(".");
+      buf.append('.');
       for (StackTraceElement element : t.getStackTrace()) {
         buf.append(" at ");
         buf.append(element.toString());
       }
-      buf.append("]");
+      buf.append(']');
     }
   }
 }

dd-java-agent/agent-logs-intake/src/main/java/datadog/trace/logging/intake/LogsDispatcher.java

@@ -66,21 +66,21 @@ public void dispatch(List<Map<String, Object>> messages) {
       }
 
       if (batchCount + 1 > maxBatchRecords || batchLength + bytes.length >= maxBatchBytes) {
-        flush(batch.append("]"));
+        flush(batch.append(']'));
         batch = new StringBuilder("[");
         batchCount = 0;
         batchLength = 0;
       }
 
       if (batchCount != 0) {
-        batch.append(",");
+        batch.append(',');
       }
       batch.append(json);
       batchCount += 1;
       batchLength += bytes.length;
     }
 
-    flush(batch.append("]"));
+    flush(batch.append(']'));
   }
 
   private void flush(StringBuilder batch) {

dd-java-agent/agent-profiling/profiling-ddprof/src/main/java/com/datadog/profiling/ddprof/DatadogProfiler.java

@@ -299,7 +299,7 @@ String cmdStartProfiling(Path file) throws IllegalStateException {
       // wall profiling is enabled.
       cmd.append(",wall=");
       if (getWallCollapsing(configProvider)) {
-        cmd.append("~");
+        cmd.append('~');
       }
       cmd.append(getWallInterval(configProvider)).append('m');
       if (getWallContextFilter(configProvider)) {

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/InstrumenterMetrics.java

@@ -206,7 +206,7 @@ private static void summarize(StringBuilder buf, String prefix, AtomicLong stat)
     long value = stat.get();
     buf.append(prefix)
         .append(String.format("%-12d", value >>> COUNT_SHIFT))
-        .append(" ")
+        .append(' ')
         .append(String.format("%.1f", (value & NANOS_MASK) / 1_000_000.0))
         .append(" ms\n");
   }

dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/MuzzleVersionScanPlugin.java

@@ -159,26 +159,26 @@ private static String prettyPrint(final String prefix, final Reference ref) {
     builder.append(Reference.prettyPrint(ref.flags));
     builder.append(ref.className);
     if (ref.superName != null) {
-      builder.append(" extends<").append(ref.superName).append(">");
+      builder.append(" extends<").append(ref.superName).append('>');
     }
     if (ref.interfaces.length > 0) {
       builder.append(" implements ");
       for (final String iface : ref.interfaces) {
-        builder.append(" <").append(iface).append(">");
+        builder.append(" <").append(iface).append('>');
       }
     }
     for (final String source : ref.sources) {
-      builder.append("\n").append(prefix).append(prefix);
+      builder.append('\n').append(prefix).append(prefix);
       builder.append("Source: ").append(source);
     }
     for (final Reference.Field field : ref.fields) {
-      builder.append("\n").append(prefix).append(prefix);
+      builder.append('\n').append(prefix).append(prefix);
       builder.append("Field: ");
       builder.append(Reference.prettyPrint(field.flags));
       builder.append(field);
     }
     for (final Reference.Method method : ref.methods) {
-      builder.append("\n").append(prefix).append(prefix);
+      builder.append('\n').append(prefix).append(prefix);
       builder.append("Method: ");
       builder.append(Reference.prettyPrint(method.flags));
       builder.append(method);

dd-java-agent/instrumentation/aws-java-eventbridge-2.0/src/main/java/datadog/trace/instrumentation/aws/v2/eventbridge/EventBridgeInterceptor.java

@@ -65,7 +65,7 @@ public SdkRequest modifyRequest(
       }
 
       detailBuilder
-          .append("\"")
+          .append('\"')
           .append(PathwayContext.DATADOG_KEY)
           .append("\": ")
           .append(traceContext)
@@ -104,7 +104,7 @@ private String getTraceContextToInject(
         .append(RESOURCE_NAME_KEY)
         .append("\": \"")
         .append(eventBusName)
-        .append("\"");
+        .append('\"');
 
     jsonBuilder.append('}');
     return jsonBuilder.toString();

dd-java-agent/instrumentation/aws-java-sns-1.0/src/main/java/datadog/trace/instrumentation/aws/v1/sns/SnsInterceptor.java

@@ -36,13 +36,13 @@ private ByteBuffer getMessageAttributeValueToInject(
       AmazonWebServiceRequest request, String snsTopicName) {
     final AgentSpan span = newSpan(request);
     StringBuilder jsonBuilder = new StringBuilder();
-    jsonBuilder.append("{");
+    jsonBuilder.append('{');
     propagate().inject(span, jsonBuilder, SETTER, TracePropagationStyle.DATADOG);
     if (traceConfig().isDataStreamsEnabled()) {
       propagate().injectPathwayContext(span, jsonBuilder, SETTER, getTags(snsTopicName));
     }
     jsonBuilder.setLength(jsonBuilder.length() - 1); // Remove the last comma
-    jsonBuilder.append("}");
+    jsonBuilder.append('}');
     return ByteBuffer.wrap(jsonBuilder.toString().getBytes(StandardCharsets.UTF_8));
   }
 

dd-java-agent/instrumentation/aws-java-sns-1.0/src/main/java/datadog/trace/instrumentation/aws/v1/sns/TextMapInjectAdapter.java

@@ -8,6 +8,6 @@ public class TextMapInjectAdapter implements AgentPropagation.Setter<StringBuild
 
   @Override
   public void set(final StringBuilder builder, final String key, final String value) {
-    builder.append("\"").append(key).append("\":\"").append(value).append("\",");
+    builder.append('\"').append(key).append("\":\"").append(value).append("\",");
   }
 }

dd-java-agent/instrumentation/aws-java-sns-2.0/src/main/java/datadog/trace/instrumentation/aws/v2/sns/SnsInterceptor.java

@@ -36,13 +36,13 @@ private SdkBytes getMessageAttributeValueToInject(
       ExecutionAttributes executionAttributes, String snsTopicName) {
     final AgentSpan span = executionAttributes.getAttribute(SPAN_ATTRIBUTE);
     StringBuilder jsonBuilder = new StringBuilder();
-    jsonBuilder.append("{");
+    jsonBuilder.append('{');
     propagate().inject(span, jsonBuilder, SETTER);
     if (traceConfig().isDataStreamsEnabled()) {
       propagate().injectPathwayContext(span, jsonBuilder, SETTER, getTags(snsTopicName));
     }
     jsonBuilder.setLength(jsonBuilder.length() - 1); // Remove the last comma
-    jsonBuilder.append("}");
+    jsonBuilder.append('}');
     return SdkBytes.fromString(jsonBuilder.toString(), StandardCharsets.UTF_8);
   }
 

dd-java-agent/instrumentation/aws-java-sns-2.0/src/main/java/datadog/trace/instrumentation/aws/v2/sns/TextMapInjectAdapter.java

@@ -8,6 +8,6 @@ public class TextMapInjectAdapter implements AgentPropagation.Setter<StringBuild
 
   @Override
   public void set(final StringBuilder builder, final String key, final String value) {
-    builder.append("\"").append(key).append("\":\"").append(value).append("\",");
+    builder.append('\"').append(key).append("\":\"").append(value).append("\",");
   }
 }

dd-java-agent/instrumentation/jakarta-rs-annotations-3/src/main/java/datadog/trace/instrumentation/jakarta3/JakartaRsAnnotationsDecorator.java

@@ -179,7 +179,7 @@ private String buildRoutePath(final Path classPath, final Path methodPath) {
     boolean skipSlash = false;
     if (classPath != null) {
       if (!classPath.value().startsWith("/")) {
-        route.append("/");
+        route.append('/');
       }
       route.append(classPath.value());
       skipSlash = classPath.value().endsWith("/");
@@ -192,7 +192,7 @@ private String buildRoutePath(final Path classPath, final Path methodPath) {
           path = path.length() == 1 ? "" : path.substring(1);
         }
       } else if (!path.startsWith("/")) {
-        route.append("/");
+        route.append('/');
       }
       route.append(path);
     }

dd-java-agent/instrumentation/jax-rs-annotations-1/src/main/java/datadog/trace/instrumentation/jaxrs1/JaxRsAnnotationsDecorator.java

@@ -170,7 +170,7 @@ private String buildRoutePath(final Path classPath, final Path methodPath) {
     boolean skipSlash = false;
     if (classPath != null) {
       if (!classPath.value().startsWith("/")) {
-        route.append("/");
+        route.append('/');
       }
       route.append(classPath.value());
       skipSlash = classPath.value().endsWith("/");
@@ -183,7 +183,7 @@ private String buildRoutePath(final Path classPath, final Path methodPath) {
           path = path.length() == 1 ? "" : path.substring(1);
         }
       } else if (!path.startsWith("/")) {
-        route.append("/");
+        route.append('/');
       }
       route.append(path);
     }