[Java] [Vertx] Use pascalcase instead of double lambda

[rohitsanj]

Follow up task from #18630, see this comment.

Existing unit test in JavaClientCodeGenTest covers the change in this PR.

openapi-generator/modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java

Lines 1002 to 1033 in 926a07f

	@Test
	public void testVertXAuthInfoWithHyphenSeparatedSecurityScheme() throws Exception {
	Map<String, Object> properties = new HashMap<>();
	properties.put(CodegenConstants.API_PACKAGE, "xyz.abcdef.api");
	File output = Files.createTempDirectory("test").toFile();
	output.deleteOnExit();
	final CodegenConfigurator configurator = new CodegenConfigurator()
	.setGeneratorName("java")
	.setLibrary(JavaClientCodegen.VERTX)
	.setAdditionalProperties(properties)
	.setInputSpec("src/test/resources/3_0/ping-with-hyphen-separated-security-scheme.yaml")
	.setOutputDir(output.getAbsolutePath().replace("\\", "/"));
	final ClientOptInput clientOptInput = configurator.toClientOptInput();
	DefaultGenerator generator = new DefaultGenerator();
	List<File> files = generator.opts(clientOptInput).generate();
	// Test that hyphen-separated security scheme names does not
	// break the Java VertX client code generation
	validateJavaSourceFiles(files);
	// Test that the name was correctly transformed to camelCase
	// starting with an uppercase letter
	TestUtils.assertFileContains(
	Paths.get(output + "/src/main/java/xyz/abcdef/ApiClient.java"),
	"public static class AuthInfo {",
	"public void addHyphenatedNameTestAuthentication(String bearerToken) {",
	"public static AuthInfo forHyphenatedNameTestAuthentication(String bearerToken) {"
	);
	}

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