[Spring] fix nullable map properties (#16524)

* fix map in spring generators

* fix nullable map in spring generators

samples/server/petstore/springboot-beanvalidation-no-nullable/.openapi-generator/FILES

@@ -52,6 +52,7 @@ src/main/java/org/openapitools/model/ModelApiResponse.java
 src/main/java/org/openapitools/model/ModelList.java
 src/main/java/org/openapitools/model/ModelReturn.java
 src/main/java/org/openapitools/model/Name.java
+src/main/java/org/openapitools/model/NullableMapProperty.java
 src/main/java/org/openapitools/model/NumberOnly.java
 src/main/java/org/openapitools/model/Order.java
 src/main/java/org/openapitools/model/OuterComposite.java

samples/server/petstore/springboot-beanvalidation-no-nullable/src/main/java/org/openapitools/model/NullableMapProperty.java

@@ -0,0 +1,94 @@
+package org.openapitools.model;
+
+import java.net.URI;
+import java.util.Objects;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import io.swagger.annotations.ApiModel;
+import io.swagger.annotations.ApiModelProperty;
+import java.util.HashMap;
+import java.util.Map;
+import java.time.OffsetDateTime;
+import javax.validation.Valid;
+import javax.validation.constraints.*;
+
+
+import java.util.*;
+import javax.annotation.Generated;
+
+/**
+ * NullableMapProperty
+ */
+
+@Generated(value = "org.openapitools.codegen.languages.SpringCodegen")
+public class NullableMapProperty {
+
+  @Valid
+  private Map<String, String> languageValues;
+
+  public NullableMapProperty languageValues(Map<String, String> languageValues) {
+    this.languageValues = languageValues;
+    return this;
+  }
+
+  public NullableMapProperty putLanguageValuesItem(String key, String languageValuesItem) {
+    if (this.languageValues == null) {
+      this.languageValues = new HashMap<>();
+    }
+    this.languageValues.put(key, languageValuesItem);
+    return this;
+  }
+
+  /**
+   * Get languageValues
+   * @return languageValues
+  */
+  
+  @ApiModelProperty(value = "")
+  @JsonProperty("languageValues")
+  public Map<String, String> getLanguageValues() {
+    return languageValues;
+  }
+
+  public void setLanguageValues(Map<String, String> languageValues) {
+    this.languageValues = languageValues;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    NullableMapProperty nullableMapProperty = (NullableMapProperty) o;
+    return Objects.equals(this.languageValues, nullableMapProperty.languageValues);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(languageValues);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class NullableMapProperty {\n");
+    sb.append("    languageValues: ").append(toIndentedString(languageValues)).append("\n");
+    sb.append("}");
+    return sb.toString();
+  }
+
+  /**
+   * Convert the given object to string with each line indented by 4 spaces
+   * (except the first line).
+   */
+  private String toIndentedString(Object o) {
+    if (o == null) {
+      return "null";
+    }
+    return o.toString().replace("\n", "\n    ");
+  }
+}
+

samples/server/petstore/springboot-beanvalidation-no-nullable/src/main/resources/openapi.yaml

@@ -2186,6 +2186,14 @@ components:
         property name with spaces:
           type: string
       type: object
+    NullableMapProperty:
+      properties:
+        languageValues:
+          additionalProperties:
+            type: string
+          nullable: true
+          type: object
+      type: object
     updatePetWithForm_request:
       properties:
         name: