Fix ConcurrentModificationException #6732

Author: neugartf

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

@@ -5,8 +5,12 @@
 
 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;
+import java.util.stream.Collectors;
 import javax.annotation.Nullable;
 
 /**
@@ -33,10 +37,15 @@ 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());
+
  String systemProperty =
- System.getProperties().entrySet().stream()
- .filter(entry -> normalizedKey.equals(normalizePropertyKey(entry.getKey().toString())))
- .map(entry -> entry.getValue().toString())
+  properties.stream()
+ .filter(entry -> normalizedKey.equals(normalizePropertyKey(entry.getKey())))
+ .map(Map.Entry::getValue)
  .findFirst()
  .orElse(null);
  if (systemProperty != null) {