Extract common content length parsing code into method (#8884)

Author: laurit

instrumentation/servlet/servlet-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/snippet/Servlet3SnippetInjectingResponseWrapper.java

@@ -75,19 +75,17 @@ public boolean containsHeader(String name) {
 
   @Override
   public void setHeader(String name, String value) {
-    // checking content-type is just an optimization to avoid unnecessary parsing
-    if ("Content-Length".equalsIgnoreCase(name) && isContentTypeTextHtml()) {
-      try {
-        contentLength = Long.parseLong(value);
-      } catch (NumberFormatException ex) {
-        logger.log(FINE, "NumberFormatException", ex);
-      }
-    }
+    handleHeader(name, value);
     super.setHeader(name, value);
   }
 
   @Override
   public void addHeader(String name, String value) {
+    handleHeader(name, value);
+    super.addHeader(name, value);
+  }
+
+  private void handleHeader(String name, String value) {
     // checking content-type is just an optimization to avoid unnecessary parsing
     if ("Content-Length".equalsIgnoreCase(name) && isContentTypeTextHtml()) {
       try {
@@ -96,7 +94,6 @@ public void addHeader(String name, String value) {
         logger.log(FINE, "Failed to parse the Content-Length header", ex);
       }
     }
-    super.addHeader(name, value);
   }
 
   @Override

instrumentation/servlet/servlet-5.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v5_0/snippet/Servlet5SnippetInjectingResponseWrapper.java

@@ -66,19 +66,17 @@ public boolean containsHeader(String name) {
 
   @Override
   public void setHeader(String name, String value) {
-    // checking content-type is just an optimization to avoid unnecessary parsing
-    if ("Content-Length".equalsIgnoreCase(name) && isContentTypeTextHtml()) {
-      try {
-        contentLength = Long.parseLong(value);
-      } catch (NumberFormatException ex) {
-        logger.log(FINE, "NumberFormatException", ex);
-      }
-    }
+    handleHeader(name, value);
     super.setHeader(name, value);
   }
 
   @Override
   public void addHeader(String name, String value) {
+    handleHeader(name, value);
+    super.addHeader(name, value);
+  }
+
+  private void handleHeader(String name, String value) {
     // checking content-type is just an optimization to avoid unnecessary parsing
     if ("Content-Length".equalsIgnoreCase(name) && isContentTypeTextHtml()) {
       try {
@@ -87,7 +85,6 @@ public void addHeader(String name, String value) {
         logger.log(FINE, "Failed to parse the Content-Length header", ex);
       }
     }
-    super.addHeader(name, value);
   }
 
   @Override