Assign string value in constructor

As you seemed to ignore my suggestion to create an MCVE, I've attempted to do so using the code from your question, and it works for me.

The code you've posted is obviously heavily edited from what you're actually doing, so I had to guess a few things, and there are also a few syntax errors in the examples you've posted, so I've attempted to infer what they really are in your code. Here's what I've done that works, along with notes about where I've guessed, hopefully it will point you in the right direction.

So, from the beginning, here's the class with @SpringBootApplication, presumably you have something like this somewhere in your codebase:

@SpringBootApplication
public class CSVExampleApplication {
    public static void main(String[] args) {
        SpringApplication.run(CSVExampleApplication.class, args);
    }
}

Here's the configuration properties class. Note that you don't need it to be an @Component.

@ConfigurationProperties("csv")
public class CSVProperties {
    private String firstCsv;

    public String getFirstCsv() {
        return firstCsv;
    }

    public void setFirstCsv(String firstCsv) {
        this.firstCsv = firstCsv;
    }
}

I called the property firstCsv to match the value from your application.yml file which is first-csv. It's interesting that in your code you seem to be referring to this property with csvProperties.getMockCSV(). I'm guessing that's just a typo in your question, because that will never work - the property name needs to match the key in your application.yml file.

Here's the configuration class. You haven't shown this anywhere in your examples, but presumably you have an equivalent somewhere. The important part is the @EnableConfigurationProperties, which must specify the class that has the @ConfigurationProperties annotation.

@Configuration
@EnableConfigurationProperties(CSVProperties.class)
public class CSVExampleConfiguration {
    private final CSVProperties csvProperties;

    @Autowired
    public CSVExampleConfiguration(CSVProperties csvProperties) {
        this.csvProperties = csvProperties;
    }

    @Bean
    @Profile("!development")
    public MockData createProductionMockData() {
        return new MockData("production");
    }

    @Bean
    @Profile("development")
    public MockData createMockData() {
        return new MockData(csvProperties.getFirstCsv());
    }
}

It's also interesting that in your question you say you're creating the bean with a method that looks like public CreateMockData createMockData() {, but then you return a MockData. Again, I'm guessing this is a typo in your question, as it won't compile like this (unless MockData extends CreateMockData, but that seems odd).

I'm not sure how you're setting the production profile, but hopefully what I've done above is a reasonable equivalent - @Profile("!development") says "create this bean if the 'development' profile is not set"

My application.yml file is also slightly different from what you've posted in your question:

spring:
  profiles: development

csv:
  first-csv: classpath:/first.csv

Your example won't work at all, firstly because you're missing a : after spring, and secondly because you seem to have csv nested under spring, which isn't how you set the configuration properties - it needs to be at the root level as above. Again, I assume these are just typos in the question because you say the application starts (which it wouldn't with the missing :) and that you see the configuration property get set (which it wouldn't with csv nested under spring).

Finally, I tested all this with a simple controller. You haven't given any details about the rest of your application, but this is what I've done, which hopefully mimics your code:

@RestController
public class TestController {
    private final MockData mockData;

    @Autowired
    public TestController(MockData mockData) {
        this.mockData = mockData;
    }

    @RequestMapping(value = "/foo", method = RequestMethod.GET)
    public String getCsv() {
        return mockData.getCSV();
    }
}

So, then, with the application running and no profile set, if I visit http://localhost:8080/foo in a browser, I get the String "production" in the response, and if I restart the application, with a profile of "development", I get a response of "classpath:/first.csv".

I appreciate that this probably isn't the "just do this" answer that you might have hoped for, but I'd suggest you compare this to your code, and try to modify anything that differs. If you still can't get it to work, then there must be some other differences elsewhere in your application that are causing the problem. If you need more help, edit your question with the specifics that I've missed, but please try to post actual code (copy and pasted, not re-typed, to avoid introducing confusing typos).