Fix empty string handling for TruncatingBufferedWriter (#2609)

Co-authored-by: Volkan Yazıcı <volkan@yazi.ci>

Author: bayne

log4j-layout-template-json-test/src/test/java/org/apache/logging/log4j/layout/template/json/util/TruncatingBufferedWriterTest.java

@@ -38,12 +38,20 @@ void test_okay_payloads() {
         writer.write(new char[] {Character.MIN_VALUE, Character.MAX_VALUE});
         writer.write("foo");
         writer.write("foobar", 3, 3);
+        writer.write("empty", 3, 0);
         writer.write(new char[] {'f', 'o', 'o', 'b', 'a', 'r', 'b', 'u', 'z', 'z'}, 6, 4);
+        writer.write(new char[] {'a', 'b', 'c'}, 0, 0);
+        writer.write(new char[] {}, 0, 0);
+        writer.write(new char[] {});
+        writer.write("", 0, 0);
+        writer.write("");
         writer.append('!');
         writer.append("yo");
         writer.append(null);
         writer.append("yo dog", 3, 6);
         writer.append(null, -1, -1);
+        writer.append("", -1, -1);
+        writer.append("");
 
         // Verify accessors.
         final char[] expectedBuffer = new char[capacity];

log4j-layout-template-json/src/main/java/org/apache/logging/log4j/layout/template/json/util/TruncatingBufferedWriter.java

@@ -77,6 +77,11 @@ public void write(final char[] source, final int offset, final int length) {
 
         // Check arguments.
         Objects.requireNonNull(source, "source");
+
+        if (source.length == 0) {
+            return;
+        }
+
         if (offset < 0 || offset >= source.length) {
             throw new IndexOutOfBoundsException("invalid offset: " + offset);
         }
@@ -126,6 +131,11 @@ public void write(final String string, final int offset, final int length) {
 
         // Check arguments.
         Objects.requireNonNull(string, "string");
+
+        if (string.isEmpty()) {
+            return;
+        }
+
         if (offset < 0 || offset >= string.length()) {
             throw new IndexOutOfBoundsException("invalid offset: " + offset);
         }
@@ -168,6 +178,11 @@ public Writer append(final CharSequence seq, final int start, final int end) {
             return this;
         }
 
+        // Short-circuit on empty sequence
+        if (seq.length() == 0) {
+            return this;
+        }
+
         // Check arguments.
         if (start < 0 || start >= seq.length()) {
             throw new IndexOutOfBoundsException("invalid start: " + start);