diff --git a/CHANGELOG.md b/CHANGELOG.md
index 233e0c85a9..9be7c73287 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -45,7 +45,7 @@ This section is for maintaining a changelog for all breaking changes for the cli
 ### Fixed
 - Fix integer overflow for variables in indices stats response ([#877](https://github.com/opensearch-project/opensearch-java/pull/877))
 - Support weight function in function score query ([#880](https://github.com/opensearch-project/opensearch-java/pull/880))
-- Fix pattern replace by making flag optional as on api  ([#895](https://github.com/opensearch-project/opensearch-java/pull/895))
+- Fix pattern replace by making flag and replacement optional as on api  ([#895](https://github.com/opensearch-project/opensearch-java/pull/895))
 
 ### Security
 
diff --git a/java-client/src/main/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilter.java b/java-client/src/main/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilter.java
index 264a29b3ca..287842be57 100644
--- a/java-client/src/main/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilter.java
+++ b/java-client/src/main/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilter.java
@@ -52,6 +52,7 @@ public class PatternReplaceCharFilter extends CharFilterBase implements CharFilt
 
     private final String pattern;
 
+    @Nullable
     private final String replacement;
 
     // ---------------------------------------------------------------------------------------------
@@ -61,8 +62,7 @@ private PatternReplaceCharFilter(Builder builder) {
 
         this.flags = builder.flags;
         this.pattern = ApiTypeHelper.requireNonNull(builder.pattern, this, "pattern");
-        this.replacement = ApiTypeHelper.requireNonNull(builder.replacement, this, "replacement");
-
+        this.replacement = builder.replacement;
     }
 
     public static PatternReplaceCharFilter of(Function<Builder, ObjectBuilder<PatternReplaceCharFilter>> fn) {
@@ -93,7 +93,7 @@ public final String pattern() {
     }
 
     /**
-     * Required - API name: {@code replacement}
+     * API name: {@code replacement}
      */
     public final String replacement() {
         return this.replacement;
@@ -104,17 +104,18 @@ protected void serializeInternal(JsonGenerator generator, JsonpMapper mapper) {
         generator.write("type", "pattern_replace");
         super.serializeInternal(generator, mapper);
 
-        if (this.flags != null) {
-            generator.writeKey("flags");
-            generator.write(this.flags);
-        }
-
         generator.writeKey("pattern");
         generator.write(this.pattern);
 
-        generator.writeKey("replacement");
-        generator.write(this.replacement);
+        if (this.replacement != null) {
+            generator.writeKey("replacement");
+            generator.write(this.replacement);
+        }
 
+        if (this.flags != null) {
+            generator.writeKey("flags");
+            generator.write(this.flags);
+        }
     }
 
     // ---------------------------------------------------------------------------------------------
@@ -129,6 +130,7 @@ public static class Builder extends CharFilterBase.AbstractBuilder<Builder> impl
 
         private String pattern;
 
+        @Nullable
         private String replacement;
 
         /**
@@ -148,9 +150,9 @@ public final Builder pattern(String value) {
         }
 
         /**
-         * Required - API name: {@code replacement}
+         * API name: {@code replacement}
          */
-        public final Builder replacement(String value) {
+        public final Builder replacement(@Nullable String value) {
             this.replacement = value;
             return this;
         }
diff --git a/java-client/src/test/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilterTest.java b/java-client/src/test/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilterTest.java
index 031b1edf33..46bbdce85b 100644
--- a/java-client/src/test/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilterTest.java
+++ b/java-client/src/test/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilterTest.java
@@ -18,6 +18,12 @@
 public class PatternReplaceCharFilterTest {
     @Test
     public void testCreatePatternReplaceCharFilter() {
+        PatternReplaceCharFilter patternReplaceCharFilter = new PatternReplaceCharFilter.Builder().pattern("pattern").build();
+        assertEquals("pattern", patternReplaceCharFilter.pattern());
+    }
+
+    @Test
+    public void testCreatePatternReplaceCharFilterWithReplacement() {
         PatternReplaceCharFilter patternReplaceCharFilter = new PatternReplaceCharFilter.Builder().pattern("pattern")
             .replacement("replacement")
             .build();