<executions>
          <execution>
            <id>add-benchmark-sources</id>
            <phase>generate-test-sources</phase>
            <goals><goal>add-test-source</goal></goals>
            <configuration>
              <sources>
                <source>benchmark</source>
              </sources>
            </configuration>
          </execution>
        </executions>
      </plugin>

        if (!source.isEmpty()) {
          return false;
        }
      }
      return true;
    }

    @Override
    public Optional<Long> lengthIfKnown() {
      long result = 0L;
      for (CharSource source : sources) {
        Optional<Long> lengthIfKnown = source.lengthIfKnown();
        if (!lengthIfKnown.isPresent()) {
          return Optional.absent();
        }

   *
   * @param sources the sources to concatenate
   * @return a {@code ByteSource} containing the concatenated data
   * @throws NullPointerException if any of {@code sources} is {@code null}
   * @since 15.0
   */
  public static ByteSource concat(ByteSource... sources) {
    return concat(ImmutableList.copyOf(sources));
  }

  /**

import java.io.File;
import java.io.IOException;

/**
 * A test factory for byte or char sources or sinks. In addition to creating sources or sinks, the
 * factory specifies what content should be expected to be read from a source or contained in a sink
 * given the content data that was used to create the source or that was written to the sink.
 *

  }

  public void testContentEquals() throws IOException {
    assertTrue(source.contentEquals(source));
    assertTrue(source.wasStreamOpened() && source.wasStreamClosed());

    ByteSource equalSource = new TestByteSource(bytes);
    assertTrue(source.contentEquals(equalSource));
    assertTrue(new TestByteSource(bytes).contentEquals(source));

    assertEquals(STRING.length(), source.copyTo(sink));
    assertTrue(source.wasStreamOpened() && source.wasStreamClosed());
    assertTrue(sink.wasStreamOpened() && sink.wasStreamClosed());

    assertEquals(STRING, sink.getString());
  }

  public void testRead_toString() throws IOException {
    assertEquals(STRING, source.read());
    assertTrue(source.wasStreamOpened() && source.wasStreamClosed());
  }

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
      </plugin>
      <plugin>
        <artifactId>maven-source-plugin</artifactId>
        <executions>
          <execution>
            <id>attach-test-sources</id>
            <phase>post-integration-test</phase>
            <goals><goal>test-jar</goal></goals>
          </execution>
        </executions>
      </plugin>

  }

  public void testContentEquals() throws IOException {
    assertTrue(source.contentEquals(source));
    assertTrue(source.wasStreamOpened() && source.wasStreamClosed());

    ByteSource equalSource = new TestByteSource(bytes);
    assertTrue(source.contentEquals(equalSource));
    assertTrue(new TestByteSource(bytes).contentEquals(source));

 * interface easier to implement for certain types of data sources.
 *
 * <p>{@code Iterator} requires its implementations to support querying the end-of-data status
 * without changing the iterator's state, using the {@link #hasNext} method. But many data sources,
 * such as {@link java.io.Reader#read()}, do not expose this information; the only way to discover

import java.io.File;
import java.io.IOException;

/**
 * A test factory for byte or char sources or sinks. In addition to creating sources or sinks, the
 * factory specifies what content should be expected to be read from a source or contained in a sink
 * given the content data that was used to create the source or that was written to the sink.
 *