diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
index 788e74c42ec1..44fa54695702 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/OpenAPINormalizer.java
@@ -232,7 +232,10 @@ public void processRules(Map<String, String> inputRules) {
                 LOGGER.error("FILTER rule must be in the form of `operationId:name1|name2|name3`: {}", inputRules.get(FILTER));
             } else {
                 if ("operationId".equals(filterStrs[0])) {
-                    operationIdFilters = new HashSet<>(Arrays.asList(filterStrs[1].split("[|]")));
+                    operationIdFilters = Arrays.stream(filterStrs[1].split("[|]"))
+                            .filter(Objects::nonNull)
+                            .map(String::trim)
+                            .collect(Collectors.toCollection(HashSet::new));
                 } else {
                     LOGGER.error("FILTER rule must be in the form of `operationId:name1|name2|name3`: {}", inputRules.get(FILTER));
                 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
index c7713234d74a..21f36c1ee6a9 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/OpenAPINormalizerTest.java
@@ -486,6 +486,24 @@ public void testFilter() {
         assertEquals(openAPI.getPaths().get("/person/display/{personId}").getPut().getExtensions().get("x-internal"), true);
     }
 
+    @Test
+    public void testFilterWithTrim() {
+        OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_0/enableKeepOnlyFirstTagInOperation_test.yaml");
+
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getExtensions(), null);
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getExtensions().get("x-internal"), true);
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getPut().getExtensions(), null);
+
+        Map<String, String> options = new HashMap<>();
+        options.put("FILTER", "operationId:\n\t\t\t\tdelete|\n\t\tlist");
+        OpenAPINormalizer openAPINormalizer = new OpenAPINormalizer(openAPI, options);
+        openAPINormalizer.normalize();
+
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getGet().getExtensions().get("x-internal"), false);
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getDelete().getExtensions().get("x-internal"), false);
+        assertEquals(openAPI.getPaths().get("/person/display/{personId}").getPut().getExtensions().get("x-internal"), true);
+    }
+
     @Test
     public void testComposedSchemaDoesNotThrow() {
         OpenAPI openAPI = TestUtils.parseSpec("src/test/resources/3_1/composed-schema.yaml");