To remove cross module internal utility usage from trace propagators (#8955)

Co-authored-by: Jack Berg <34418638+jack-berg@users.noreply.github.com>

Author: NithinU2802

…metry/api/internal/TemporaryBuffers.java …telemetry/api/impl/TemporaryBuffers.javaapi/all/src/main/java/io/opentelemetry/api/internal/TemporaryBuffers.java renamed to api/all/src/main/java/io/opentelemetry/api/impl/TemporaryBuffers.java api/all/src/main/java/io/opentelemetry/api/internal/TemporaryBuffers.java renamed to api/all/src/main/java/io/opentelemetry/api/impl/TemporaryBuffers.java

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-package io.opentelemetry.api.internal;
+package io.opentelemetry.api.impl;
 
 /**
  * {@link ThreadLocal} buffers for use when creating new derived objects such as {@link String}s.
@@ -12,8 +12,8 @@
  * should get a temporary buffer, fill it with data, and finish by converting into the derived
  * object within the same method to avoid multiple usages of the same buffer.
  *
- * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
- * at any time.
+ * <p>This class is not intended for use by application developers. Its API is stable and will not
+ * be changed or removed in a backwards-incompatible manner.
  */
 public final class TemporaryBuffers {
 
@@ -24,6 +24,9 @@ public final class TemporaryBuffers {
    * {@code len} as this buffer will remain for the lifetime of the thread. The returned buffer will
    * not be zeroed and may be larger than the requested size, you must make sure to fill the entire
    * content to the desired value and set the length explicitly when converting to a {@link String}.
+   *
+   * @param len the minimum buffer capacity
+   * @return a reusable thread-local character buffer with capacity of at least {@code len}
    */
   public static char[] chars(int len) {
     char[] buffer = CHAR_ARRAY.get();

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

@@ -20,6 +20,7 @@
 
 package io.opentelemetry.api.internal;
 
+import io.opentelemetry.api.impl.TemporaryBuffers;
 import javax.annotation.CheckForNull;
 
 /**

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

@@ -5,7 +5,6 @@
 
 package io.opentelemetry.api.internal;
 
-import java.util.Objects;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
@@ -32,52 +31,6 @@ public static boolean isNullOrEmpty(@Nullable String string) {
     return string == null || string.isEmpty();
   }
 
-  /**
-   * Pads a given string on the left with leading 0's up the length.
-   *
-   * @param value the string to pad
-   * @param minLength the minimum length the resulting padded string must have. Can be zero or
-   *     negative, in which case the input string is always returned.
-   * @return the padded string
-   */
-  public static String padLeft(String value, int minLength) {
-    return padStart(value, minLength, '0');
-  }
-
-  /**
-   * Returns a string, of length at least {@code minLength}, consisting of {@code string} prepended
-   * with as many copies of {@code padChar} as are necessary to reach that length. For example,
-   *
-   * <ul>
-   *   <li>{@code padStart("7", 3, '0')} returns {@code "007"}
-   *   <li>{@code padStart("2010", 3, '0')} returns {@code "2010"}
-   * </ul>
-   *
-   * <p>See {@link java.util.Formatter} for a richer set of formatting capabilities.
-   *
-   * <p>This method was copied almost verbatim from Guava library method
-   * com.google.common.base.Strings#padStart(java.lang.String, int, char).
-   *
-   * @param string the string which should appear at the end of the result
-   * @param minLength the minimum length the resulting string must have. Can be zero or negative, in
-   *     which case the input string is always returned.
-   * @param padChar the character to insert at the beginning of the result until the minimum length
-   *     is reached
-   * @return the padded string
-   */
-  private static String padStart(String string, int minLength, char padChar) {
-    Objects.requireNonNull(string);
-    if (string.length() >= minLength) {
-      return string;
-    }
-    StringBuilder sb = new StringBuilder(minLength);
-    for (int i = string.length(); i < minLength; i++) {
-      sb.append(padChar);
-    }
-    sb.append(string);
-    return sb.toString();
-  }
-
   /**
    * Determines whether the {@code String} contains only printable characters.
    *

api/all/src/main/java/io/opentelemetry/api/trace/SpanId.java

@@ -5,8 +5,8 @@
 
 package io.opentelemetry.api.trace;
 
+import io.opentelemetry.api.impl.TemporaryBuffers;
 import io.opentelemetry.api.internal.OtelEncodingUtils;
-import io.opentelemetry.api.internal.TemporaryBuffers;
 import io.opentelemetry.common.impl.ApiUsageLogger;
 import javax.annotation.concurrent.Immutable;
 

api/all/src/main/java/io/opentelemetry/api/trace/TraceId.java

@@ -5,8 +5,8 @@
 
 package io.opentelemetry.api.trace;
 
+import io.opentelemetry.api.impl.TemporaryBuffers;
 import io.opentelemetry.api.internal.OtelEncodingUtils;
-import io.opentelemetry.api.internal.TemporaryBuffers;
 import io.opentelemetry.common.impl.ApiUsageLogger;
 import javax.annotation.concurrent.Immutable;
 

api/all/src/main/java/io/opentelemetry/api/trace/propagation/W3CTraceContextPropagator.java

@@ -8,8 +8,8 @@
 import static io.opentelemetry.api.trace.propagation.internal.W3CTraceContextEncoding.decodeTraceState;
 import static io.opentelemetry.api.trace.propagation.internal.W3CTraceContextEncoding.encodeTraceState;
 
+import io.opentelemetry.api.impl.TemporaryBuffers;
 import io.opentelemetry.api.internal.OtelEncodingUtils;
-import io.opentelemetry.api.internal.TemporaryBuffers;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanContext;
 import io.opentelemetry.api.trace.SpanId;

…y/api/internal/TemporaryBuffersTest.java …metry/api/impl/TemporaryBuffersTest.javaapi/all/src/test/java/io/opentelemetry/api/internal/TemporaryBuffersTest.java renamed to api/all/src/test/java/io/opentelemetry/api/impl/TemporaryBuffersTest.java api/all/src/test/java/io/opentelemetry/api/internal/TemporaryBuffersTest.java renamed to api/all/src/test/java/io/opentelemetry/api/impl/TemporaryBuffersTest.java

@@ -3,7 +3,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-package io.opentelemetry.api.internal;
+package io.opentelemetry.api.impl;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

api/all/src/test/java/io/opentelemetry/api/internal/StringUtilsTest.java

@@ -6,7 +6,6 @@
 package io.opentelemetry.api.internal;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import org.junit.jupiter.api.Test;
 
@@ -27,22 +26,4 @@ void isNullOrEmpty() {
     assertThat(StringUtils.isNullOrEmpty("hello")).isFalse();
     assertThat(StringUtils.isNullOrEmpty(" ")).isFalse();
   }
-
-  @Test
-  void padLeft() {
-    assertThat(StringUtils.padLeft("value", 10)).isEqualTo("00000value");
-  }
-
-  @Test
-  void padLeft_throws_for_null_value() {
-    assertThatThrownBy(() -> StringUtils.padLeft(null, 10))
-        .isInstanceOf(NullPointerException.class);
-  }
-
-  @Test
-  void padLeft_length_does_not_exceed_length() {
-    assertThat(StringUtils.padLeft("value", 3)).isEqualTo("value");
-    assertThat(StringUtils.padLeft("value", -10)).isEqualTo("value");
-    assertThat(StringUtils.padLeft("value", 0)).isEqualTo("value");
-  }
 }

docs/apidiffs/current_vs_latest/opentelemetry-api.txt

@@ -7,3 +7,7 @@ Comparing source compatibility of opentelemetry-api-1.68.0-SNAPSHOT.jar against
 	+++  NEW METHOD: PUBLIC(+) STATIC(+) boolean isValidBase16String(java.lang.CharSequence)
 	+++  NEW METHOD: PUBLIC(+) STATIC(+) long longFromBase16String(java.lang.CharSequence, int)
 	+++  NEW METHOD: PUBLIC(+) STATIC(+) void longToBase16String(long, char[], int)
++++  NEW CLASS: PUBLIC(+) FINAL(+) io.opentelemetry.api.impl.TemporaryBuffers  (not serializable)
+	+++  CLASS FILE FORMAT VERSION: 52.0 <- n.a.
+	+++  NEW SUPERCLASS: java.lang.Object
+	+++  NEW METHOD: PUBLIC(+) STATIC(+) char[] chars(int)

extensions/trace-propagators/src/main/java/io/opentelemetry/extension/trace/propagation/B3PropagatorExtractorSingleHeader.java

@@ -5,7 +5,6 @@
 
 package io.opentelemetry.extension.trace.propagation;
 
-import io.opentelemetry.api.internal.StringUtils;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.context.propagation.TextMapGetter;
@@ -34,7 +33,7 @@ public <C> Optional<Context> extract(
   private static <C> Optional<Context> extractSpanContextFromSingleHeader(
       Context context, @Nullable C carrier, TextMapGetter<C> getter) {
     String value = getter.get(carrier, B3Propagator.COMBINED_HEADER);
-    if (StringUtils.isNullOrEmpty(value)) {
+    if (value == null || value.isEmpty()) {
       return Optional.empty();
     }