NPE for parameter without a name

Description

Codegen throws a NPE when generating code for a buggy declaration that has parameters without a name. Happens at least with nodejs-server and python-flask, but not with any client codegens I've tried, so maybe this is a server-only issue?

Swagger-codegen version

Current master

Swagger declaration file content or url

swagger: "2.0"
paths:
  /:
    get:
      operationId: foo
      parameters:
        - bug-here:
          in: query
          type: string

Steps to reproduce

$ java -jar swagger-codegen-cli.jar generate -i bug.yml -l nodejs-server
[main] INFO io.swagger.parser.Swagger20Parser - reading from bug.yml
[main] INFO io.swagger.codegen.ignore.CodegenIgnoreProcessor - No .swagger-codegen-ignore file found.
Exception in thread "main" java.lang.RuntimeException: Could not process operation:
  Tag: default
  Operation: foo
  Resource: get /
  Definitions: {}
  Exception: null
    at io.swagger.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:808)
    at io.swagger.codegen.DefaultGenerator.processPaths(DefaultGenerator.java:700)
    at io.swagger.codegen.DefaultGenerator.generate(DefaultGenerator.java:377)
    at io.swagger.codegen.cmd.Generate.run(Generate.java:223)
    at io.swagger.codegen.SwaggerCodegen.main(SwaggerCodegen.java:36)
Caused by: java.lang.NullPointerException
    at java.util.regex.Matcher.getTextLength(Matcher.java:1283)
    at java.util.regex.Matcher.reset(Matcher.java:309)
    at java.util.regex.Matcher.<init>(Matcher.java:229)
    at java.util.regex.Pattern.matcher(Pattern.java:1093)
    at io.swagger.codegen.DefaultCodegen.camelize(DefaultCodegen.java:2875)
    at io.swagger.codegen.DefaultCodegen.fromProperty(DefaultCodegen.java:1385)
    at io.swagger.codegen.DefaultCodegen.fromParameter(DefaultCodegen.java:2227)
    at io.swagger.codegen.DefaultCodegen.fromOperation(DefaultCodegen.java:1993)
    at io.swagger.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:756)
    ... 4 more

Suggest a Fix

Should probably ignore parameters without a name, and output a warning message about them (along with input filename, linenumber if possible). Or fail with a descriptive message.

Reproduce the failure with bug.yml through the swagger-codegen-cli.jar generate entry point, using nodejs-server or python-flask. Start with DefaultCodegen.fromParameter, DefaultCodegen.fromProperty, and DefaultCodegen.camelize, following the stack trace from DefaultGenerator.processOperation. Done means an unnamed parameter no longer causes an NPE and is either skipped with a warning or rejected with a descriptive error.