public void setConcurrencyLevel(int concurrencyLevel) {
    if (concurrencyLevel <= 0) {
      throw new IllegalArgumentException(
          "concurrencyLevel must be > 0");
    }
    regionAttributes.concurrencyLevel = concurrencyLevel;
    regionAttributes.setHasConcurrencyLevel(true);
  }
Sets the concurrency level of the next {@code RegionAttributes} created. This value is used in
initializing the map that holds the entries. Default is 16.

@param concurrencyLevel the concurrency level of the entry map
@throws IllegalArgumentException if concurrencyLevel is nonpositive
geode-core/src/main/java/org/apache/geode/cache/AttributesFactory.java