[NEW BUG]: Avoid allocations in String.replace(CharSequence, CharSequence) in case no replacement happened

[Christoph Dreis]

Hey Vitaly,

Thanks for clearing the way. 

As all things seem to be clarified now, is there someone who is willing to sponsor the patch?

Cheers,
Christoph

====== PATCH ======

diff --git a/src/java.base/share/classes/java/lang/String.java b/src/java.base/share/classes/java/lang/String.jav
--- a/src/java.base/share/classes/java/lang/String.java
+++ b/src/java.base/share/classes/java/lang/String.java
@@ -2177,11 +2177,13 @@
      */
     public String replace(CharSequence target, CharSequence replacement) {
         String tgtStr = target.toString();
-        String replStr = replacement.toString();
         int j = indexOf(tgtStr);
         if (j < 0) {
+            // Explicit nullcheck of replacement to fulfill NPE contract in early out
+            Objects.requireNonNull(replacement);
             return this;
         }
+        String replStr = replacement.toString();
         int tgtLen = tgtStr.length();
         int tgtLen1 = Math.max(tgtLen, 1);
         int thisLen = length();