package io.quarkus.cache.runtime;

import java.util.Collections;
import java.util.Map;
import java.util.Optional;
import java.util.Set;

import javax.enterprise.context.ApplicationScoped;

import io.quarkus.cache.Cache;
import io.quarkus.cache.CacheManager;

@ApplicationScoped
public class CacheManagerImpl implements CacheManager {

    // There's no need for concurrency here since the caches are created at build time and never modified after that.
    private Map<String, Cache> caches;
    private Set<String> cacheNames;

    public void setCaches(Map<String, Cache> caches) {
        if (this.caches != null) {
            throw new IllegalStateException("The caches map must only be set once at build time");
        }
        this.caches = Collections.unmodifiableMap(caches);
        cacheNames = Collections.unmodifiableSet(caches.keySet());
    }

    @Override
    public Set<String> getCacheNames() {
        return cacheNames;
    }

    @Override
    public Optional<Cache> getCache(String name) {
        if (name == null) {
            return Optional.empty();
        }
        return Optional.ofNullable(caches.get(name));
    }
}

package io.quarkus.cache.runtime;

import java.util.Collections;
import java.util.Map;
import java.util.Optional;
import java.util.Set;

import javax.enterprise.context.ApplicationScoped;

import io.quarkus.cache.Cache;
import io.quarkus.cache.CacheManager;

@ApplicationScoped
public class CacheManagerImpl implements CacheManager {

    // There's no need for concurrency here since the caches are created at build time and never modified after that.
    private Map<String, Cache> caches = Collections.emptyMap();
    private Set<String> cacheNames = Collections.emptySet();

    public void setCaches(Map<String, Cache> caches) {
        if (this.caches != Collections.EMPTY_MAP) {
            throw new IllegalStateException("The caches map must only be set once at build time");
        }
        this.caches = Collections.unmodifiableMap(caches);
        cacheNames = Collections.unmodifiableSet(caches.keySet());
    }

    @Override
    public Set<String> getCacheNames() {
        return cacheNames;
    }

    @Override
    public Optional<Cache> getCache(String name) {
        if (name == null) {
            return Optional.empty();
        }
        return Optional.ofNullable(caches.get(name));
    }
}

Fix NPE in CacheManagerImpl