[Java] Fixes Spring generator devaultValues for int64/float/double

Created by: spacether

This PR fixes https://github.com/OpenAPITools/openapi-generator/issues/1226 That issue describes that when we have an in64, float, or double CodegenParameter, the string defaultValue includes unneeded suffix characters l,f, or d. Those suffixes were added by AbstractJavaCodegen because that generator assumed that those default values would be used as java values of the correct type. Instead, the spring generator uses String type default values for CodegenParameter only. Typically those values are handled with parseLong/parseFloat/parseDouble etc which fail if the value includes a character suffix.

This update keeps the suffixes on CodegenProperties because templates use those defaultValues as Long/Float/Double literal values. CodegenProperty defaultValues:

• "9223372036854775807l" (int64)
• "3.14159f" (float)
• "3.14159d" (double)

For CodegenParameter we now use values which lack the suffix so parseLong/parseDouble/parseFloat will work CodegenParameter defaultValues:

• "9223372036854775807" (int64)
• "3.14159" (float)
• "3.14159" (double)

Further work

I verified that all spring generators use classes that require String defaultValues for query params. These are:

1. spring-mvc-petstore-server (ApiParam,RequestParam String defaultValue)
2. spring-cloud-feign-petstore (ApiParam, RequestParam String defaultValue)
3. spring-cloud-feign-async-petstore (ApiParam, RequestParam String defaultValue)
4. spring-stubs (ApiParam, RequestParam String defaultValue)
5. spring-mvc-petstore-j8-async-server (ApiParam, RequestParam String defaultValue)
6. spring-mvc-petstore-j8-localdatetime (ApiParam, RequestParam String defaultValue)
7. spring-delegate (ApiParam, RequestParam String defaultValue)
8. spring-delegate-j8 (ApiParam, RequestParam String defaultValue)
9. springboot-petstore-server (ApiParam, RequestParam String defaultValue)
10. springboot-petstore-server-reactive (ApiParam, RequestParam String defaultValue)
11. springboot-petstore-server-beanvalidation (ApiParam, RequestParam String defaultValue)
12. springboot-petstore-server-implicitHeaders (ApiParam, RequestParam String defaultValue)
13. springboot-petstore-server-useOptional (ApiParam, RequestParam String defaultValue)
14. springboot-virtualan-petstore-server (ApiParam, RequestParam String defaultValue)

Verification Test

• A test has been added at https://github.com/spacether/openapi-generator/blob/issue_1226_fix_defaultValue/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java#L485

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
• File the PR against the correct branch: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

Java Technical Committee: @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10)