[BUG][Java] emitting non-compilable code with map&&!container

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Don't have a minimized reproduction example yet, but it is triggered on recursive syntax tree schema on 5.x+ openapi-generator (also latest 6.2.0).
Following part of template in java pojo.mustache

  {{#isMap}}

  public {{classname}} put{{nameInCamelCase}}Item(String key, {{{items.datatypeWithEnum}}} {{name}}Item) {
    {{#vendorExtensions.x-is-jackson-optional-nullable}}
    if (this.{{name}} == null || !this.{{name}}.isPresent()) {
      this.{{name}} = JsonNullable.<{{{datatypeWithEnum}}}>of({{{defaultValue}}});
    }

emits code like

  public SyntaxTree putNotItem(String key,  notItem) {
    this.not.put(key, notItem);
    return this;
  }

notice that items.datatypeWithEnum is empty and notItem breaks compilation.
Adding {{#isContainer}} in addition to {{#isMap}} fixes it by not emitting a wrong method (setNot method is the only one needed and it is still emitted)

openapi-generator version

6.2.0, seems to have started since 5.x

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

Not sure if isMap&&!isContainer a valid combination. Fix could either to update template as mentioned above or fixing isMap detection

Start with the Java pojo.mustache template and reproduce the issue using a recursive syntax tree schema. Inspect the isMap and isContainer conditions around the map item method, then verify that generated Java no longer contains an empty item type and compiles successfully.