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

docs/generators/java-camel.md

@@ -40,7 +40,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |camelUseDefaulValidationtErrorProcessor|generate default validation error processor| |true|
 |camelValidationErrorProcessor|validation error processor bean name| |validationErrorProcessor|
 |configPackage|configuration package for generated code| |org.openapitools.configuration|
-|dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app only)</dd><dt>**legacy**</dt><dd>Legacy java.util.Date (if you really have a good reason not to use threetenbp</dd><dt>**java8-localdatetime**</dt><dd>Java 8 using LocalDateTime (for legacy app only)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for jdk 1.8+) - note: this also sets &quot;java8&quot; to true</dd><dt>**threetenbp**</dt><dd>Backport of JSR310 (preferred for jdk &lt; 1.8)</dd></dl>|threetenbp|
+|dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app only)</dd><dt>**legacy**</dt><dd>Legacy java.util.Date</dd><dt>**java8-localdatetime**</dt><dd>Java 8 using LocalDateTime (for legacy app only)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for jdk 1.8+)</dd></dl>|java8|
 |delegatePattern|Whether to generate the server files using the delegate pattern| |false|
 |developerEmail|developer email in generated pom.xml| |team@openapitools.org|
 |developerName|developer name in generated pom.xml| |OpenAPI-Generator Contributors|
@@ -60,7 +60,6 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |implicitHeaders|Skip header parameters in the generated API methods using @ApiImplicitParams annotation.| |false|
 |interfaceOnly|Whether to generate only API interface stubs without the server files.| |false|
 |invokerPackage|root package for generated code| |org.openapitools.api|
-|java8|Use Java8 classes instead of third party equivalents. Starting in 5.x, JDK8 is the default and the support for JDK7, JDK6 has been dropped|<dl><dt>**true**</dt><dd>Use Java 8 classes such as Base64. Use java8 default interface when a responseWrapper is used. IMPORTANT: This option has been deprecated as Java 8 is the default.</dd><dt>**false**</dt><dd>Various third party libraries as needed</dd></dl>|true|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |library|library template (sub-template)|<dl><dt>**spring-boot**</dt><dd>Spring-boot Server application using the SpringFox integration.</dd><dt>**spring-mvc**</dt><dd>Spring-MVC Server application using the SpringFox integration.</dd><dt>**spring-cloud**</dt><dd>Spring-Cloud-Feign client with Spring-Boot auto-configured settings.</dd></dl>|spring-boot|
 |licenseName|The name of the license| |Unlicense|