Improve stream handling of system property

Author: neugartf

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

@@ -5,11 +5,9 @@
 
 package io.opentelemetry.api.internal;
 
-import java.util.AbstractMap;
 import java.util.Locale;
 import java.util.Map;
-import java.util.Set;
-import java.util.stream.Collectors;
+import java.util.Objects;
 import javax.annotation.Nullable;
 
 /**
@@ -36,18 +34,12 @@ private ConfigUtil() {}
  */
  public static String getString(String key, String defaultValue) {
  String normalizedKey = normalizePropertyKey(key);
- Set<Map.Entry<String, String>> properties =
- 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()
- .filter(entry -> normalizedKey.equals(normalizePropertyKey(entry.getKey())))
- .map(Map.Entry::getValue)
+ System.getProperties().stringPropertyNames().stream()
+ .filter(propertyName -> normalizedKey.equals(normalizePropertyKey(propertyName)))
+ .map(System::getProperty)
+ .filter(Objects::nonNull)
  .findFirst()
  .orElse(null);
  if (systemProperty != null) {