diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AdaCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AdaCodegen.java
index 42865b4cbcd1..fd7f105715b9 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AdaCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AdaCodegen.java
@@ -21,11 +21,10 @@
 import java.io.IOException;
 import java.io.Writer;
 
+import org.apache.commons.lang3.StringUtils;
 import com.samskivert.mustache.Mustache;
 import com.samskivert.mustache.Template;
 import org.openapitools.codegen.*;
-import org.openapitools.codegen.utils.ModelUtils;
-
 
 public class AdaCodegen extends AbstractAdaCodegen implements CodegenConfig {
 
@@ -54,7 +53,7 @@ public void processOpts() {
         if (additionalProperties.containsKey(CodegenConstants.PACKAGE_NAME)) {
             packageName = (String) additionalProperties.get(CodegenConstants.PACKAGE_NAME);
         }
-        if (packageName == "") {
+        if (StringUtils.isEmpty(packageName)) {
             packageName = modelPackage;
         }
         String srcPrefix = "src" + File.separator;
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
index fa103a1a3256..db7799d827b2 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppPistacheServerCodegen.java
@@ -170,7 +170,7 @@ public CodegenOperation fromOperation(String path, String httpMethod, Operation
                 if (response != null) {
                     CodegenProperty cm = fromProperty("response", response);
                     op.vendorExtensions.put("x-codegen-response", cm);
-                    if (cm.datatype == "HttpContent") {
+                    if ("HttpContent".equals(cm.datatype)) {
                         op.vendorExtensions.put("x-codegen-response-ishttpcontent", true);
                     }
                 }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java
index 2cde67af48ab..3e7f02671ab9 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppQt5ClientCodegen.java
@@ -53,7 +53,7 @@ public CppQt5ClientCodegen() {
         outputFolder = "generated-code/qt5cpp";
 
         // set modelNamePrefix as default for QT5CPP
-        if ("".equals(modelNamePrefix)) {
+        if (StringUtils.isEmpty(modelNamePrefix)) {
             modelNamePrefix = PREFIX;
         }
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java
index 5e17b9197338..d5cce8cb2ee4 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppRestClientCodegen.java
@@ -241,7 +241,7 @@ public CodegenOperation fromOperation(String path, String httpMethod, Operation
                 if (response != null) {
                     CodegenProperty cm = fromProperty("response", response);
                     op.vendorExtensions.put("x-codegen-response", cm);
-                    if (cm.datatype == "HttpContent") {
+                    if ("HttpContent".equals(cm.datatype)) {
                         op.vendorExtensions.put("x-codegen-response-ishttpcontent", true);
                     }
                 }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppTizenClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppTizenClientCodegen.java
index cb5aed630a00..e419d4270351 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppTizenClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/CppTizenClientCodegen.java
@@ -281,7 +281,7 @@ public String escapeReservedWord(String name) {
     @Override
     public String toOperationId(String operationId) {
         // throw exception if method name is empty
-        if ("".equals(operationId)) {
+        if (StringUtils.isEmpty(operationId)) {
             throw new RuntimeException("Empty method name (operationId) not allowed");
         }
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaInflectorServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaInflectorServerCodegen.java
index e4443782b826..d403f1562a77 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaInflectorServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaInflectorServerCodegen.java
@@ -20,6 +20,7 @@
 import io.swagger.v3.oas.models.Operation;
 
 import org.apache.commons.lang3.BooleanUtils;
+import org.apache.commons.lang3.StringUtils;
 import org.openapitools.codegen.CodegenModel;
 import org.openapitools.codegen.CodegenOperation;
 import org.openapitools.codegen.CodegenProperty;
@@ -107,7 +108,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             basePath = basePath.substring(0, pos);
         }
 
-        if (basePath == "") {
+        if (StringUtils.isEmpty(basePath)) {
             basePath = "default";
         } else {
             if (co.path.startsWith("/" + basePath)) {
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJAXRSSpecServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJAXRSSpecServerCodegen.java
index e4dc8a90ca68..ed0a18fc8f40 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJAXRSSpecServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJAXRSSpecServerCodegen.java
@@ -19,6 +19,7 @@
 
 import io.swagger.v3.oas.models.Operation;
 
+import org.apache.commons.lang3.StringUtils;
 import org.openapitools.codegen.CliOption;
 import org.openapitools.codegen.CodegenConstants;
 import org.openapitools.codegen.CodegenModel;
@@ -147,7 +148,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             basePath = basePath.substring(0, pos);
         }
 
-        if (basePath == "") {
+        if (StringUtils.isEmpty(basePath)) {
             basePath = "default";
         } else {
             if (co.path.startsWith("/" + basePath)) {
@@ -156,7 +157,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             co.subresourceOperation = !co.path.isEmpty();
         }
         List<CodegenOperation> opList = operations.get(basePath);
-        if (opList == null) {
+        if (opList == null || opList.isEmpty()) {
             opList = new ArrayList<CodegenOperation>();
             operations.put(basePath, opList);
         }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJerseyServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJerseyServerCodegen.java
index 86947dd58a93..387d75dead6f 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJerseyServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaJerseyServerCodegen.java
@@ -18,7 +18,6 @@
 package org.openapitools.codegen.languages;
 
 import org.openapitools.codegen.*;
-import org.openapitools.codegen.languages.features.BeanValidationFeatures;
 import io.swagger.v3.oas.models.*;
 
 import java.util.*;
@@ -171,7 +170,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
                 basePath = basePath.substring(0, pos);
             }
 
-            if (basePath == "") {
+            if (StringUtils.isEmpty(basePath)) {
                 basePath = "default";
             } else {
                 if (co.path.startsWith("/" + basePath)) {
@@ -180,7 +179,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
                 co.subresourceOperation = !co.path.isEmpty();
             }
             List<CodegenOperation> opList = operations.get(basePath);
-            if (opList == null) {
+            if (opList == null || opList.isEmpty()) {
                 opList = new ArrayList<CodegenOperation>();
                 operations.put(basePath, opList);
             }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaMSF4JServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaMSF4JServerCodegen.java
index 8bb85d0fcc2a..046a3084de1f 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaMSF4JServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaMSF4JServerCodegen.java
@@ -152,7 +152,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             basePath = basePath.substring(0, pos);
         }
 
-        if (basePath == "") {
+        if (StringUtils.isEmpty(basePath)) {
             basePath = "default";
         } else {
             if (co.path.startsWith("/" + basePath)) {
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyEapServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyEapServerCodegen.java
index e59d6f85656f..22e874ba6006 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyEapServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyEapServerCodegen.java
@@ -126,7 +126,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             basePath = basePath.substring(0, pos);
         }
 
-        if (basePath == "") {
+        if (StringUtils.isEmpty("")) {
             basePath = "default";
         } else {
             if (co.path.startsWith("/" + basePath)) {
@@ -135,7 +135,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             co.subresourceOperation = !co.path.isEmpty();
         }
         List<CodegenOperation> opList = operations.get(basePath);
-        if (opList == null) {
+        if (opList == null || opList.isEmpty()) {
             opList = new ArrayList<CodegenOperation>();
             operations.put(basePath, opList);
         }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyServerCodegen.java
index 16b1135d8d6b..52b0ab16d967 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaResteasyServerCodegen.java
@@ -18,7 +18,6 @@
 package org.openapitools.codegen.languages;
 
 import org.openapitools.codegen.*;
-import org.openapitools.codegen.languages.features.BeanValidationFeatures;
 import org.openapitools.codegen.languages.features.JbossFeature;
 import io.swagger.v3.oas.models.*;
 import org.apache.commons.lang3.BooleanUtils;
@@ -129,7 +128,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             basePath = basePath.substring(0, pos);
         }
 
-        if (basePath == "") {
+        if (StringUtils.isEmpty(basePath)) {
             basePath = "default";
         } else {
             if (co.path.startsWith("/" + basePath)) {
@@ -138,7 +137,7 @@ public void addOperationToGroup(String tag, String resourcePath, Operation opera
             co.subresourceOperation = !co.path.isEmpty();
         }
         List<CodegenOperation> opList = operations.get(basePath);
-        if (opList == null) {
+        if (opList == null || opList.isEmpty()) {
             opList = new ArrayList<CodegenOperation>();
             operations.put(basePath, opList);
         }