Remove the option to support JDK7 from Java generator and templates (#11547)

* remove java8 from java client generator and templates

* update tests

* remove threetenbp

* update spring templates to remove java8

* remove java8 from jaxrs template

* fix jaxrs spec

* fix feign

* remove CustomInstantDeserializer.java

* fix jersey1

* fix undertow

* various update

* fix jaxrs jersey1

* fix java inflector

* fix jaxrs cxf

* add new files

* update doc

samples/client/petstore/java/feign-no-nullable/pom.xml

@@ -263,9 +263,9 @@
             <version>${jackson-databind-version}</version>
         </dependency>
         <dependency>
-          <groupId>com.github.joschi.jackson</groupId>
-          <artifactId>jackson-datatype-threetenbp</artifactId>
-          <version>${jackson-threetenbp-version}</version>
+          <groupId>com.fasterxml.jackson.datatype</groupId>
+          <artifactId>jackson-datatype-jsr310</artifactId>
+          <version>${jackson-version}</version>
         </dependency>
         <dependency>
             <groupId>com.github.scribejava</groupId>
@@ -327,7 +327,6 @@
         <feign-form-version>3.8.0</feign-form-version>
         <jackson-version>2.10.3</jackson-version>
         <jackson-databind-version>2.10.3</jackson-databind-version>
-        <jackson-threetenbp-version>2.9.10</jackson-threetenbp-version>
         <jakarta-annotation-version>1.3.5</jakarta-annotation-version>
         <junit-version>5.7.0</junit-version>
         <maven-plugin-version>1.0.0</maven-plugin-version>