Move to stringPropertyNames in order to iterate on a stable list.

Author: neugartf

api/all/src/main/java/io/opentelemetry/api/internal/ConfigUtil.java

@@ -6,7 +6,6 @@
 package io.opentelemetry.api.internal;
 
 import java.util.AbstractMap;
-import java.util.HashSet;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
@@ -38,15 +37,12 @@ private ConfigUtil() {}
  public static String getString(String key, String defaultValue) {
  String normalizedKey = normalizePropertyKey(key);
  Set<Map.Entry<String, String>> properties =
- new HashSet<>(System.getProperties().entrySet())
- .stream()
- .filter(
- entry -> entry.getKey() instanceof String && entry.getValue() instanceof String)
- .map(
- entry ->
- new AbstractMap.SimpleEntry<>(
- (String) entry.getKey(), (String) entry.getValue()))
- .collect(Collectors.<Map.Entry<String, String>>toSet());
+ System.getProperties().stringPropertyNames().stream()
+ .map(
+ propertyName ->
+ new AbstractMap.SimpleEntry<>(propertyName, System.getProperty(propertyName)))
+ .filter(entry -> entry.getKey() != null)
+ .collect(Collectors.<Map.Entry<String, String>>toSet());
 
  String systemProperty =
  properties.stream()