[dynamic control] add SourceFormat string to enum conversion (#2737)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: jackshirazi

dynamic-control/src/main/java/io/opentelemetry/contrib/dynamic/policy/source/SourceFormat.java

@@ -7,7 +7,9 @@
 
 import com.google.errorprone.annotations.Immutable;
 import java.util.List;
+import java.util.Locale;
 import java.util.Objects;
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 /** Supported source formats and their parser dispatch. */
@@ -27,6 +29,28 @@ public String configValue() {
     return configValue;
   }
 
+  /**
+   * Converts string value case insensitively to enum value. Leading and trailing whitespace is
+   * removed, then the remainder is matched case-insensitively against {@link #configValue()} for
+   * each format.
+   *
+   * @param value the string from config (e.g. {@code "keyvalue"}, {@code "JSONKEYVALUE"})
+   * @return the matching format
+   * @throws NullPointerException if value is null
+   * @throws IllegalArgumentException if no format matches the trimmed value
+   */
+  public static SourceFormat fromConfigValue(@Nonnull String value) {
+    Objects.requireNonNull(value, "value cannot be null");
+    String normalized = value.trim().toLowerCase(Locale.ROOT);
+    for (SourceFormat format : values()) {
+      if (format.configValue.equals(normalized)) {
+        return format;
+      }
+    }
+    throw new IllegalArgumentException(
+        "Unknown source format (normalized): '" + normalized + "' (original: '" + value + "')");
+  }
+
   /**
    * Parses source text into normalized wrappers for this format.
    *

dynamic-control/src/test/java/io/opentelemetry/contrib/dynamic/policy/source/SourceFormatTest.java

@@ -19,6 +19,27 @@ void configValuesAreStable() {
     assertThat(SourceFormat.KEYVALUE.configValue()).isEqualTo("keyvalue");
   }
 
+  @Test
+  void fromConfigValueParsesCaseInsensitive() {
+    assertThat(SourceFormat.fromConfigValue("KEYVALUE")).isEqualTo(SourceFormat.KEYVALUE);
+    assertThat(SourceFormat.fromConfigValue("JsonKeyValue")).isEqualTo(SourceFormat.JSONKEYVALUE);
+  }
+
+  @Test
+  void fromConfigValueTrimsWhitespace() {
+    assertThat(SourceFormat.fromConfigValue("  keyvalue  ")).isEqualTo(SourceFormat.KEYVALUE);
+  }
+
+  @Test
+  void fromConfigValueRejectsNullAndUnknown() {
+    assertThatThrownBy(() -> SourceFormat.fromConfigValue(null))
+        .isInstanceOf(NullPointerException.class)
+        .hasMessage("value cannot be null");
+    assertThatThrownBy(() -> SourceFormat.fromConfigValue("other"))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("Unknown source format (normalized): 'other' (original: 'other')");
+  }
+
   @Test
   void parseDelegatesToJsonParser() {
     List<SourceWrapper> parsed = SourceFormat.JSONKEYVALUE.parse("{\"trace-sampling\": 0.5}");